Early years

Martin turned professional in 2008 with Slipstream–Chipotle. In 2008, he won the Route du Sud and the Irish National Road Race Championships. In 2009, Martin reached a UCI World Rankings of thirty-fifth (137 points), and rode his first Grand Tour, the 2009 Vuelta a España. In 2010, he won his first UCI ProTour stage race, the Tour of Poland.^[10] He finished forty-ninth in the 2010 UCI World Rankings (106 points); Ireland placed seventeenth in the national rankings (254 points).

2011

Martin participating in the 2011 Critérium du Dauphiné.

2011 was Martin's break-out season. He won his first Grand Tour stage during the Vuelta a España, and became the first Irishman to hold the mountains classification; he wore the mountains jersey for stages ten and eleven.^[8][17] Martin won Stage 6 and finished second overall, behind Slovak Peter Sagan of Liquigas–Cannondale, in the Tour of Poland. With a second place, behind Leopard Trek's Oliver Zaugg of Switzerland, in the season-ending Giro di Lombardia, Martin finished in ninth in the UCI World Rankings (286 points); Ireland placed thirteenth in the national rankings (319 points).

2012

Whilst achieving no wins in 2012, Martin placed sixteenth in UCI World Ranking (196 points); Ireland finished sixteenth in the national rankings (259 points).

2013

Martin riding to victory at the 2013 Liège–Bastogne–Liège

In March 2013, Martin won Stage 4 of the Volta a Catalunya; his fourth World Tour victory.^[18] Martin gained the leader's jersey the following day, and won overall classification four days later.^[11] In April, Martin finished fourth in La Flèche Wallonne; the following weekend, he won Liège–Bastogne–Liège, beating Team Katusha's Joaquim Rodríguez of Spain.^[12] It was during the final stages of this race that a spectator in a panda suit chased the riders, leading to a long-lasting connection between Martin and the panda.^[19] Martin's form continued at the Tour de Suisse where he placed eighth overall.

Martin, along with his teammates Andrew Talansky and Ryder Hesjedal, rode the Tour de France as co-captains. On Stage 8, finishing at Ax 3 Domaines, Talansky and Martin finished together, twelfth and thirtieth, respectively, to sit twelfth and thirteenth overall.^[20] The following day, Martin won Stage 9 in Bagnères-de-Bigorre, after escaping from the lead group with Dane Jakob Fuglsang (Astana) on the final climb.^[21] He out sprinted Fuglsang in the final kilometre to win the stage.^[22] Martin moved up to eighth overall in the process.^[23] However, Martin fell ill in the final week, and following the final three mountain stages, slipped to thirty-third overall.^[24][25]

Martin completed the 2013 season with a fourth-place finish in the Giro di Lombardia,^[26] and a second-place finish in the Tour of Beijing.^[27] Martin finished sixth in the UCI World Rankings (432 points); Ireland placed tenth in the national rankings (568 points).

2014

Martin finished second in La Flèche Wallonne, behind Spaniard Alejandro Valverde (Movistar Team). Martin looked well positioned in Liège–Bastogne–Liège, sitting in second place, but in the final 200 metres (660 feet) he crashed; Australian Simon Gerrans (Orica–GreenEDGE) was victorious. Martin's primary focus was the Giro d'Italia, which started in Belfast. However, in the opening team time trial, Martin crashed, breaking his collarbone; he subsequently abandoned the race.^[28] He skipped the Tour de France to focus on the Vuelta a España; he placed seventh overall.^[29] In October, Martin won the Giro di Lombardia; he attacked in the final kilometre, and soloed to the finish, winning by one second.^[30] Martin won Stage 4, and placed second overall, behind BMC Racing Team's Philippe Gilbert of Belgium, at the season-ending Tour of Beijing.^[31] Martin finished ninth in the UCI World Rankings (316 points); Ireland placed fourteenth in the national rankings (357 points).

2015

In March, Martin came in tenth position at the Volta a Catalunya. He participated in Liège–Bastogne–Liège, but was caught in a pile-up and had to abandon all hopes of winning the race.^[32] He participated in the Tour de Romandie (finishing 104th) where he complained of chest pain, but only after the race was it found that he had two broken ribs, a result of his crash at Liège–Bastogne–Liège.^[33] On Stage 11 of the Tour de France, Martin rode across a three-minute gap on the Col d'Aspin to the breakaway, and then led over the top of the climb. However Rafał Majka, part of the breakaway, attacked the group on the Col du Tourmalet; Martin went over the climb in third place, and he rode with Emanuel Buchmann for a while before going solo to catch Majka. He passed Serge Pauwels but he could not quite get to Majka, but he did win the Combativity award for the stage.

2016

Martin joined Etixx–Quick-Step on a two-year contract from 2016, with a focus on strengthening the team's squad for the Ardennes classics and competing as a contender in stage races.^[34] Martin enjoyed success in his first race with his new team, winning the second stage of the Volta a la Comunitat Valenciana, his first win for over a year.^[35] He took another win against a strong field in the Volta a Catalunya,^[36] going on to finish third overall.^[37] He went on to Belgium to race in the Ardennes classics, where his best result was a third place at La Flèche Wallonne.^[38]

2017

Martin (front) at the 2017 Tour de France

Martin's first significant result of the season was a stage win at the Volta ao Algarve.^[39] In April, he placed second to Alejandro Valverde in both La Flèche Wallonne and Liège–Bastogne–Liège.^[40][41] In June, his late attack in the final stage lifted him to the podium, in third place, of the Critérium du Dauphiné, overtaking Chris Froome by a single second.^[42]

In the Tour de France, Martin was involved in a crash with Richie Porte in stage 9. In an interview at the end of the stage he said;

I guess the organisers got what they wanted. I don’t think anyone want to takes risks, but it was so slippy out there. Richie just lost it on one corner, locked his back wheel and there was nowhere to go. I was lucky to come away with what I did.^[43]

Despite back pain, finding it hard to walk and not being able to get out of his saddle at times, he went on to finish the race sixth in the general classification, only learning afterwards that he had fractured two vertebrae in the crash.^[44] The injury forced him to miss the Clásica de San Sebastián.

2018

Martin at the 2018 Liège–Bastogne–Liège

In August 2017, Martin announced that he was joining UAE Team Emirates, on a two-year contract, for the 2018 season.^[4] Martin had turned down an offer to ride for Team Sky, as he would not be a team leader in Grand Tours. He had also received interest from Bora–Hansgrohe, BMC Racing Team, Team Katusha–Alpecin and Trek–Segafredo.^[45] He made his debut for UAE Team Emirates at the Volta ao Algarve.^[46] Martin placed fourth on stage 2 of the Volta ao Algarve, by losing out on a sprint finish to Michał Kwiatkowski;^[47] he went on to finish 14th overall.

At Paris–Nice, Martin abandoned the race due to bad weather conditions and illness on Stage 7,^[48] Martin had lost time on the previous stage due to a mechanical problem with his bike.^[49] At the Volta a Catalunya Martin fell behind on Stage 4 to La Molina, finishing 1 minute 29 seconds behind stage winner Alejandro Valverde, in 19th place.^[50] He took his first win of the season with a stage win at the Critérium du Dauphiné. On 12 July Martin won his second Tour de France stage, winning stage 6 at Mûr-de-Bretagne.^[51][52] He was named the most combative rider of the Tour de France.^[53]