Martin grew up in Tamworth, Staffordshire, and was educated at St Francis of Assisi Catholic Technology College.

In 2005, he joined the French amateur team Vélo-Club La Pomme Marseille, and won the mountains classification in the Ronde de l'Isard.

In 2009, Martin reached a UCI World Rankings of thirty-fifth (137 points), and rode his first Grand Tour, the 2009 Vuelta a España.

[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.

Martin, along with his teammates Andrew Talansky and Ryder Hesjedal, rode the Tour de France as co-captains.

[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.

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.

However, in the opening team time trial, Martin crashed, breaking his collarbone; he subsequently abandoned the race.

[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.

[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.

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.

[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.

[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.