Cummings joined new British-based for the 2010 season. In 2011, racing with Sky, he had arguably his most successful professional race to date at the Volta ao Algarve. He won stage three in a mountain-top finish ahead of Alberto Contador, taking the overall lead of the race which he held until the final time-trial; he finished the tour in seventh place. In September, Cummings finished second overall in the Tour of Britain. Later that month he announced he would join for the 2012 season. Cummings was part of the Great Britain team that helped Mark Cavendish win the men's road race at the 2011 UCI Road World Championships. He then finished 4th overall in the first Tour of Beijing.
In February 2012, Cummings broke his pelvis in an accident while competing in the Volta ao Algarve. In April, bad luck struck again when he fractured his left wrist in the Tour of the Basque Country. He recuperated from those injuries and competed in the Tour de France, where he was a domestique to his leader Cadel Evans and finished 95th overall. In the 2012 Vuelta a España, he gained his first Grand Tour victory. On Stage 13, he broke away with six other riders after the first hour of racing. The break made it through on the mainly flat course and he attacked with about to race, creating a gap. He held on to his lead and won by four seconds over the two chasers, Cameron Meyer of and 's Juan Antonio Flecha.
MTN–Qhubeka/Dimension Data (2015–19)
In October 2014, Cummings announced that he would be joining for the 2015 season. On 18 July 2015, Cummings won stage 14 of the Tour de France, beating French riders Thibaut Pinot and Romain Bardet in Mende, after the Côte de la Croix Neuvecategory 2 climb. It was the first Tour de France stage win for both Cummings and his African team, fittingly coming on Mandela Day. On 8 July 2016, Cummings took another breakaway win in the Tour de France, this time on Stage 7, with a winning margin of 65 seconds over Daryl Impey and Daniel Navarro. In July 2016 he was added to Great Britain's Olympic cycling team for the Summer Olympics, replacing Peter Kennaugh. Cummings took what British journalistWilliam Fotheringham considered to be the most important stage race victory of his career to date at the Tour of Britain in September 2016. He finished 2nd on stage 2 in Kendal, Cumbria, gaining a minute over most of his rivals. He subsequently moved into the lead on stage 6 and held this position for the remaining two days. During the 2017 Tour of the Basque Country Cummings crashed heavily and required surgery. After a long period of recovery he won both the British National Time Trial Championships and the British National Road Race Championships on the Isle of Man, becoming only the second rider to win both titles in the same year after David Millar achieved the same feat in 2007. In November 2019, Cummings announced his retirement from professional cycling.
