At the Tour de l'Ain in August 2012, Majka finished second on the penultimate stage, losing out to Andrew Talansky in Septmoncel, having been part of a three-rider breakaway.

[13] He led his home race, the Tour de Pologne for three days, before losing a podium on the final 37-kilometre (23-mile) individual time trial; he won the points classification alongside his fourth-place overall finish.

[19] Majka was a last-minute inclusion in Tinkoff–Saxo's Tour de France squad, after Roman Kreuziger was temporarily suspended from racing due to irregular biological passport values.

Majka then prepared to race his season target, the Vuelta a España, attempting to gain a top 5 or podium finish in the general classification.

He performed well throughout the entire race, being able to stay near to the top of the general classification behind the likes of Tom Dumoulin, Nairo Quintana and Fabio Aru.

[39] At the Giro d'Italia, Majka raced as the leader of the Tinkoff team and finished fifth overall, four minutes behind winner Vincenzo Nibali, his best result to that point.

[40] Following the Giro d'Italia, Majka won the Polish National Road Race Championships for the first time in his career, breaking away at the front over the last climb and holding his advantage to the finish line.

On the final descent, both Nibali and Henao crashed, leaving Majka alone in front, unable to preserve his advantage over the chase group to the finish.

He was caught by eventual winner Greg Van Avermaet and Jakob Fuglsang within 2 kilometres (1.2 miles) of the finish line and did not participate in the final sprint, settling for third.

[48] At the Tour of California, Majka won the second stage in a two-up sprint against George Bennett in San Jose, and took the race lead as a result.

[49] Majka lost the race lead to Bennett on the penultimate stage, a 24-kilometre (15-mile) individual time trial around Big Bear Lake, and he ultimately finished second overall.

[62] He ultimately finished the race in sixth overall, moving up a position (ahead of Miguel Ángel López) on the final 17-kilometre (11-mile) individual time trial in Verona.

[69] Majka maintained second place overall as Simon Yates took over the race lead following stage five,[70] and ultimately finished third overall, as Geraint Thomas overhauled him in the final 10.1-kilometre (6.3-mile) individual time trial around San Benedetto del Tronto.

In October 2020, Majka signed an initial two-year contract with UAE Team Emirates from the 2021 season, where he would act as a mountain domestique for Tadej Pogačar, who had won the Tour de France the previous month.

[80] At June's Tour of Slovenia, Majka and Pogačar were part of a three-rider move – along with Domen Novak – that went clear of the field with around 60 kilometres (37 miles) remaining on the opening stage.

[90] He rode the Tour de France in support of team leader Pogačar, who had been aiming to regain his title following Jonas Vingegaard's victory in 2022.

[94] Majka then contested the Tour de Pologne, in support of team leader João Almeida, where he won the third stage of the race – on a steep uphill finish in Duszniki-Zdrój – by a wheel length from Matej Mohorič and Michał Kwiatkowski.