Early years (1988–1993)

Since its launch on April 1, 1979, and throughout the 1980s, Nickelodeon aired programs for preschoolers (most prominently Pinwheel and Today's Special) on weekdays (from 8:00 am – 2:00 pm) and weekend mornings. After Nickelodeon's preschool block premiered a slew of new shows in 1987, it began using the Nick Junior branding on January 4, 1988 (1988-01-04), coinciding with the premiere of the Spanish program The World of David the Gnome. A new rebrand for the block that abbreviated its name to Nick Jr. was gradually unveiled September 5, 1988.^[1] Nick Jr.'s new logo was orange for 'Nick' and blue for 'Jr.', and it varied in the shape or species (e.g.: two gears, trains, robots, planets, insects, comets, or elephants). Like with Nickelodeon, Nick Jr.'s network IDs featured the block's logo in different shapes and styles. At launch, the block aired from 8:30 am – 2:30 pm. On weekends, preschool programs went unbranded and aired at earlier hours of the day.

Until June 29, 1990, Pinwheel was featured, originally for three hours (two in the morning and one at noon), then for one hour starting in spring 1989. When Nick Jr.'s original series Eureeka's Castle premiered in September, Pinwheel was split into two separate half hours in the morning and afternoon, where it remained until June 29, 1990, after which the block was truncated to start at 9:30 am - 2:30 pm on June 15, 1992, another solidified timing at 9:30 am - 2:00 pm on July 6, 1992 and last solidified timing at 9:00 am - 2:00 pm on October 5, 1992. Much of Nick Jr.'s other programs at the time were of Japanese or foreign origin (including Fred Penner's Place, Sharon, Lois & Bram's Elephant Show, Adventures of the Little Koala, Noozles, Maya the Bee, and The Littl' Bits).

Grow, Learn, and Play (1993–1994)

One of the many former Nick Jr. logos used from 1993 to 2009.

On April 5, 1993 (1993-04-05), Nick Jr. premiered a new series, Cappelli & Company, and received a new rebrand which prominently featured a new Nick Jr. logo consisting of an orange parent and a blue child, and the slogan Grow, Learn, and Play. Several Nick Jr. promos and bumpers featured kids playing near the Nick Jr. logo and a theme song with the slogan sung to the melody of London Bridge, and a few featured Cappelli & Company mascot Frank Cappelli. Nick Jr. also started using a female announcer (who was replaced by a different one in 1994, 1998 and 2003) in its promos and bumpers. Nick Jr. began to invest more into producing original interstitial series (including 1994's Muppet Time, forty two-minute shorts from The Jim Henson Company) in order to stay within a self-imposed limit of five minutes of commercials per hour.

On April 4, 1994, the "Jim Henson's Muppet Hour" sub-block was created by pairing Muppet Babies reruns with the new acquisition The Muppet Show. Due to Nick Jr.'s declining ratings as well as competition from PBS' PTV and TLC's Ready Set Learn, Nickelodeon spent $30 million revamping the Nick Jr. block over the next three years.^[2] On June 13, older-skewing Nickelodeon series Rugrats, The Alvin Show, Dennis the Menace, and Lassie joined Nick Jr.'s lineup, as the block's branding was temporarily de-emphasized in favor of regular Nickelodeon branding until September 2.

Just for Me/Play to Learn (1994–2003)

On September 5, 1994 (1994-09-05), Nick Jr. rebranded and introduced Face, an animated mascot that introduced shows and interstitials and led into commercial breaks. In the context of his segments, Face was capable of materializing objects such as an astronaut, a robot, a clown, a window, a traffic light, stars, and even wood. He was also capable of creating a number of foley sound effects and voices including an iconic signature three-note trumpet noise usually following the name "Nick Jr." at the end of almost every bumper. Also, he changed colors, moods, and feelings. Face was voiced by Chris Phillips, who also narrated several Nickelodeon and Nick Jr. promos. The original Face promos were produced by Nick Digital (from 1994 to 1996 and from 2000 to 2003; the later promos featured a redesigned Face) and DMA Animation (from 1996 to 2000). On October 21, Nick Jr. did away with The Elephant Show, as their investment in the show's US run was not being met, and three days later premiered two new original series, Gullah Gullah Island and Allegra's Window, resulting in 50% rating gains for the block.

In 1995, Nick Jr. acquired broadcast rights to The Busy World of Richard Scarry from sister network Showtime, and later premiered Rupert on September 11, and Little Bear on November 6 (both were produced by the Canadian animation studio Nelvana).

On September 8, 1996 (1996-09-08), the first episode of Blue's Clues premiered in primetime on Nick at Nite, then aired on Nick Jr. the next day. Nick Jr. also premiered four new interstitial series and received a new rebrand produced by Pittard Sullivan. Blue's Clues quickly deposed Gullah Gullah Island as Nick Jr.'s most popular series until Wonder Pets deposed Blue's Clues as Nick Jr's popular show when it first aired in 2006. Rugrats was pushed out of Nick Jr.'s lineup after May 2, 1997, to make room for second showings of Little Bear and Blue's Clues. The Wubbulous World of Dr. Seuss later joined the lineup on October 7, 1997, after a series of occasional airings on the block from October 21, 1996, to February 1997. On March 16, 1998, the "nickjr.com" website was launched. Later that year, Nick Jr. rebranded again and introduced the "Just for Me" slogan. A sign-on and sign-off bumper featuring the "Just for Me" slogan was used on Nick Jr. video releases from 2000–04.

In the first quarter of 1999, Nick Jr. premiered three new series based on books, Franklin on January 11, Kipper on February 8, and Maisy on the 11 of the same month, which helped increase the block's ratings. Later in 1999, Little Bill premiered on November 28; the series' first episodes premiered on Nickelodeon Sunday nights before airing on Nick Jr. the next day. Nick Jr. briefly aired reruns of Shining Time Station on June 5, 2000 (Maggie and the Ferocious Beast premiered on the same day that show premiered) to promote the film, Thomas and the Magic Railroad, before replacing it with Dora the Explorer on August 14, which became one of Nick Jr.'s most successful series.

The US dub of Bob the Builder premiered on Nickelodeon on January 13, 2001, before airing on Nick Jr. two days later. Oswald premiered on August 20. On September 3, 2001 (2001-09-03), Nick Jr. received a new rebrand produced by AdamsMorioka (who had previously rebranded Nickelodeon and Nick at Nite) and Editional Effects, intended to have a greater appeal towards parents. In the spring of 2002, Nick Jr. altered the format of its commercial breaks, resulting in the removal of older network IDs dating back to 1994. On April 7, 2003, the day that sister network Noggin rebranded and introduced Moose and Zee, Nick Jr. aired some of Noggin's new original series (Oobi, Tweenies, and Miffy and Friends) as a cross-promotion. Nick Jr. continued to air Tweenies from July to September 25.

On August 29, 2003, the original Face interstitials ended their almost 9-year run.

Play Along (2003–2004)

On September 1, 2003 (2003-09-01), Nick Jr. received a rebrand that introduced more than a dozen new logos; British program Rubbadubbers premiered the next day. A new interstitial series called Nick Jr. Play Along was introduced, hosted by two live-action hosts: Robin (played by actress Hillary Hawkins^[3]) and Zack (played by actor Travis Guba^[4]). Along with Robin and Zack were two sock puppets called the Feetbeats. Face was given a brand new look which added eyebrows and a chin and straightened his eyes by inverting their colors from white dots on black eyes to actual-looking eyes, usually referred to as "Modern Face" and was voiced by Nick on CBS announcer Babi Floyd. The new Face promos were produced by Vee-Pee Cartoons.

Nick Jr. removed the Play Along interstitials aside from a re-edited opening in February 2004.

On October 8, 2004, the new Face interstitials ended their 1-year run.^[5]

Love to Play! (2004–2007)

On October 11, 2004 (2004-10-11), Nick Jr. received another rebrand containing interstitials co-produced by Little Airplane Productions featuring the block's new mascot Piper O'Possum (voiced by Ali Brustofski and created by Josh Selig), and the new slogan "Love to Play!". Nick Jr.'s female announcer was replaced with Kobie Powell and Chris Phillips. Nick Jr. used its new on-screen bug to promote its website until March 3, 2006 (2006-03-03). LazyTown, Miss Spider's Sunny Patch Friends, Blue's Room, and The Backyardigans (the latter of which premiering alongside the rebrand) premiered on Nick Jr. in 2004. Between 2004 and 2007, Nick Jr. reduced its reliance on interstitial series and increased the amount of commercials it aired.

Dora the Explorer spin-off Go, Diego, Go! premiered in 2005, whilst Wonder Pets! and Wow! Wow! Wubbzy! debuted the following year.

On November 10, 2006, the SpongeBob SquarePants "Best Day Ever" marathon on Nickelodeon pre-empted the Nick Jr. block.

On August 20, 2007 (2007-08-20), just twenty-one days before Nick Jr.'s rebrand, Yo Gabba Gabba! debuted, and was the only Nick Jr. series to premiere that year (Ni Hao, Kai-Lan was set to premiere in late-2007, but was later delayed to premiere on February 7, 2008 (2008-02-07)).

On September 7, 2007, the Piper O'Possum interstitials ended their 3-year run.

Nick Jr.'s Play Date (2007–2009)

On September 10, 2007 (2007-09-10), Nick Jr. received yet another rebrand named Nick Jr.'s Play Date. A new slogan, Play with Us!, was also included. Nick Jr.'s bumpers encouraged preschoolers to play along and featured the Nick Jr. logo in the form of two stop-motion stuffed animals. From September 10, 2007 to February 2008, Nick Jr.'s Play Date retained the Nick Jr. on-screen bugs from 2006, only with the Play Date branding in place. Starting in February 2008, the on-screen bugs were changed to match the branding. This marked the first time that Nick Jr. had no mascot since 1994. Starting on February 25, 2008 (2008-02-25), Nick Jr. began its broadcast at 8:30 am.

After January 30, 2009, the block temporarily stopped using the Nick Jr. brand name (in order to avoid confusion with the then-upcoming channel of the same name). As a result, the Nick Jr.'s Play Date interstitials ended their 1.5-year run.

Nickelodeon rebranding (2009–2014)

Former logo used from September 28, 2009 to May 21, 2018.

On February 2, 2009 (2009-02-02), the Nick Jr. block temporarily rebranded as Nickelodeon's Play Date. NickJr.com continued to use the Nick Jr. brand name to categorize all of Nickelodeon's preschool programming. The block's new branding was designed by Melinda Beck, and many bumpers featured drawings, finger puppets or cupcakes. The bumpers' music was a choir of kids vocalizing, and Nicolette Pierini was the announcer of each bumper. With this new branding, the Nick Jr. graphic bugs were replaced with the bug used for regular Nickelodeon programming. Despite now being known as Nickelodeon's Play Date, some bumpers still contained the Nick Jr. stop motion animal bumpers from the previous branding. From February 2 to early June of that same year, Nickelodeon’s Play Date retained the Nick Jr. split-screen credits from 2007, only with the Nickelodeon splat logo in place. Starting in June of that year, the split-screen credits were changed to match the branding. On September 28 of that year, the Nick Jr. channel was launched, replacing Noggin. That same day, the block became simply known as Nick's Play Date. Starting in the summer of 2010, Nick's Play Date began its broadcast at 7:00 am.

In 2011, Nick's Play Date received a new rebrand featuring characters from the block's shows. That same year, Nick’s Play Date stopped using the branding’s split-screen credits, and started using Nickelodeon’s split-screen credits design. The following year, the Play Date branding was replaced with a modified version of the Nick Jr. channel's new branding known as Nick: The Smart Place to Play. Despite Nickelodeon displaying its shows credits during the last 30 seconds before it since 2012, the branding retained the split-screen credits for Nick Jr. shows airing on the block until May 2, 2014 (2014-05-02).

Return of Nick Jr. branding (2014–2023)

Logo used since May 21, 2018; in which the logo is in slightly darker color. Concurrently used alongside the 2023 logo since July 5, 2023.

On May 5, 2014 (2014-05-05), Nick: The Smart Place to Play rebranded back to Nick Jr. and began calling itself "Nick Jr. on Nickelodeon" or "Nick Jr. on Nick" while still using the Nickelodeon name for the screen bug. When aired on the Nick Jr. channel, commercials for programs broadcast on Nickelodeon's Nick Jr. block usually end with "Over on Nick" or "Over on Nickelodeon" to differentiate the titles. On the same day, the Nick Jr. block also began to use Nickelodeon's on-screen credits to include more commercials (now 12 minutes per hour). On June 10, 2015 (2015-06-10), the Nick Jr. website was fully redesigned to match up with the Nick Jr. app.^[6]

On May 21, 2018 (2018-05-21), the Nick Jr. block rebranded with new bumpers and curriculum boards. Starting in the fall of 2020, Nick Jr. began its broadcast at 7:00 am once again for the first time since 2010. As of fall 2022, the Nick Jr. block has been extended to sign off at 3:00 pm, but by January 2, 2023, it reverted to having a 2 p.m. sign off time.

Return of Nickelodeon branding (2023–present)

On July 5, 2023 (2023-07-05), the Nick Jr. block was rebranded to include the refreshed splat logo and used the Nickelodeon name in the refreshed bumpers, as well as refreshed curriculum boards, while the Nick Jr. channel eventually adopted the full rebrand on September 4.^[7]

Other Nick Jr. blocks for broadcast networks

From 2000 to 2002 and from 2004 to 2006, Nick Jr. programs and interstitial segments appeared as a Saturday morning block on CBS entitled Nick Jr. on CBS. From 2002 to 2004, it was part of the general Nick on CBS block, which also included programming from the main Nickelodeon channel. It ended after Viacom and CBS Corporation were separated at the start at 2006 (but re-merged in later years) and was replaced by the KOL Secret Slumber Party block on September 16, 2006.

Spanish-language US network Telemundo has aired Blue's Clues (Spanish Pista De Blues) (from 1998 to 2000, as part of the Nickelodeon en Telemundo block) and Dora the Explorer (Spanish Dora la Exploradora) (from 2005 to 2006, as part of the Telemundo Kids block) in Spanish. On April 5, 2008, competing Spanish network Univision added Spanish-dubbed versions of Dora the Explorer and its spin-off Go, Diego, Go! to their Saturday morning Planeta U line-up. A Spanish-dubbed version of The Backyardigans was later added to the lineup on January 8, 2011.

For a brief time in summer 2010, Tr3s, a sister network to Nickelodeon, aired a daily block of Spanish-dubbed Nick Jr. programs under the name Tr3s Jr. to meet E/I requirements for its broadcast affiliates. Shows like Pistas de Blue (the Spanish version of Blue's Clues) and Wonder Pets! were featured in the block.

Face's reappearances

Face (1990s) made an appearance during the 2012 New Year edition of The '90s Are All That, TeenNick's former 1990s-oriented late-night block. Face's appearances consisted of out-of-context clips that make him appear to be drunk or making adult comments (e.g.: "Yeah, grow a pair!").

In October 2015 for the Halloween/Nick or Treat season, the "Face the Monster" bumper would play on the block as a transition of introducing episodes of Aaahh!!! Real Monsters. The same bumper would be used on the block as an April Fools' Day prank on April 1, 2017.

Face also appeared in an Easter promo for The Splat, The '90s Are All That's successor, in 2016, encouraging viewers to look for the Easter bunny in 1990s Nickelodeon shows.

Face even got his own Nick Jr. show called Face's Music Party, that premiered on June 3, 2022.