New York Islanders

Weinhandl broke into the NHL during the 2002–03 season. He tallied his first NHL point (an assist) in his first NHL game on November 4, 2002 against the Calgary Flames. He picked up his first NHL goal 23 days later, on November 27, against the Ottawa Senators' goalie Patrick Lalime. He played in that season's YoungStars game, which took place in Sunrise, Florida during the All-Star break and picked up a goal and an assist. He missed a number of games during the early part of the season due to a sprained shoulder, but finished the year with 23 points (six goals and 17 assists) in 47 games.

The following season, Weinhandl was forced to start the season for the Islanders' minor league team, the Bridgeport Sound Tigers, to rehab an ankle injury that kept him out of the 2003 playoffs and required surgery over the summer. Upon being deemed fit to play for the Islanders, Weinhandl played for the most part on a line with Alexei Yashin, and notched 20 points (eight goals and 12 assists) in 55 games.

Minnesota Wild

Upon returning from his 2004–05 campaign in Sweden, Weinhandl was quickly signed to a two-year, $1.6 million contract to keep him with the Islanders. Weinhandl played mostly on the team's fourth line. He recorded six points (two goals and four assists) in 53 games for the Islanders before he was waived and claimed by the Minnesota Wild on March 4, 2006. In 15 games for Minnesota, Weinhandl picked up two goals and three assists.

In the 2006–07 season, Weinhandl was a healthy scratch in 13 of the team's first 28 games (missing an additional three games after suffering a concussion) before being waived by the Wild on December 8, 2006.

Houston Aeros

Unclaimed he was assigned to the Wild's minor league affiliate, the Houston Aeros, on December 9. Before being sent down, he tallied one goal and one assist in 12 games.

Weinhandl found some success in the minor league. He played in 48 games with the Aeros, scoring 18 goals and 27 assists with a total of 20 penalty minutes. During that span, he had several multi-point games, including four assists in one of the final games of the season.

Modo

From the 1999–00 season to the 2001–02 season, Weinhandl played for Modo in the Swedish elite league Elitserien. His first season there, he was on a very successful line with Henrik and Daniel Sedin, who each went on to have long careers with the NHL's Vancouver Canucks. The line was dubbed "Line 19", as Weinhandl and both Sedins were 19-years-of-age at the time. He returned to play for Modo again in the 2004–05 season due to the NHL lockout. Weinhandl led the team in scoring with 46 points (26 goals and 20 assists) in 50 games and was third in the league in points, behind only Henrik Zetterberg of Timrå and Kristian Huselius of Linköping, and tied with Shawn Horcoff of Mora.

Linköping

Weinhandl signed with Linköping on April 22, 2007. He signed a two-year deal worth 7.2 million Swedish kronor, with an option for a third year. During the 2007–08 season, Weinhandl enjoyed a good return to Sweden, scoring 35 goals to win the Håkan Loob Trophy. He also netted 27 assists for a total of 62 points, second in the league only to his line mate Tony Mårtensson.

Weinhandl drew the attention of the Russian Superleague (RSL) and on April 23, 2008, it was announced that he would be loaned out to Dynamo Moscow in the Russian Kontinental Hockey League (KHL) for the 2008–09 season.^[1] That same day, he also signed a contract extension with Linköping, ensuring his return and keeping him in Linköping's possession through 2012.

After Linköping's early exit in the 2009 Elitserien playoffs, it seemed that the team would bring back all of their loaned players, including Weinhandl. However, it was announced on April 14 that Weinhandl would be staying with Dynamo Moscow in Russia for another season.^[2]

On April 21, 2012, it was announced that Weinhandl would be returning to Linköping and play there for at least two more years, much to the liking of the fans.

On April 26, 2014, Weinhandl officially announced his retirement as a player due to injuries.

Dynamo Moscow

Weinhandl's first season in Russia was not quite as successful as he might have hoped — he suffered a knee injury late in the pre-season that caused him to miss the first fourteen games of the season.^[3] He finished the regular season with 16 goals and 17 assists in 41 games. Dynamo was a participant in the 2008 Spengler Cup that took place in December 2008. Weinhandl, along with his teammate Dmitry Afanasenkov, led the tournament in scoring with seven points apiece and helped Dynamo win the tournament for the second time in their history.

Weinhandl elevated his game in the 2009 KHL playoffs, scoring 16 points in 12 games, and was among the statistical leaders in several offensive categories. In addition, he was named the league's best forward in the month of March, based on his play in the playoffs. The team made it to the semi-final round, where it was eliminated by the eventual Gagarin Cup winner Ak Bars Kazan.

Weinhandl returned to Dynamo Moscow for the 2009–10 season, scoring 60 points in 56 games. This placed him again among the statistical league leaders, most notably as the top scoring foreign (non-Russian) player. He was also named best forward for the month of October. Dynamo fared poorly in the playoffs that season and was eliminated in the first round.

SKA St. Petersburg

After the 2009-2010 season, Dynamo Moscow was disbanded and Weinhandl was instead contracted by SKA St Petersburg prior to 2010-2011 season. During this season he has been reunited with his old line-mate from Linköping, Tony Mårtensson, and former Islanders teammate Alexei Yashin. SKA took part in the 2010 Spengler Cup tournament in Davos, Switzerland, in December 2010. Weinhandl helped his team beat Team Canada in the final to win the tournament for the fourth time in team history and the first time since 1977. It was also the third year in a row that a team from the KHL won the tournament.