Pimenta has competed since the late 2000s. His first major result came at the 2010 World Championships in Poznań, Poland, when he won the K-2 500 metressilver medal together with João Ribeiro. One year later, he contributed to the Portuguese K-4 1000 metresgold medal at the European Championships in Belgrade, Serbia, and claimed a bronze in the K-1 1000 metres. Together with Emanuel Silva, he won the silver medal in the K-2 1000 metres event at the 2012 Summer Olympics in London, which was Portugal's only medal at these Games. In 2013, Pimenta won multiple medals in international events, namely two silvers at the European Championships, held in Portugal's Montemor-o-Velhoracing course, and two golds at the Summer Universiade in Kazan. The following year, he secured his second world championship medal in Moscow, after a runner-up finish in the K-4 1000 metres event. At the European Championships in Brandenburg, Germany, Pimenta finished again in the top-three places of the K-1 5000 and K-4 1000 metres, taking a bronze medal in both events. Pimenta participated in the inaugural edition of the European Games, in Baku, Azerbaijan, where he became the first Portuguese sprint canoeist to win a medal in this competition, after finishing second in the K-1 1000 metres event; a day later, he added another silver medal in the K-1 5000 metres. At the World Championships in Milan, Pimenta won the K-1 1000 metres bronze medal – his third medal at this level – and secured his country's qualification for this event at the 2016 Summer Olympics in Rio de Janeiro. In 2016, Pimenta won his first individual continental titles after taking the K-1 1000 and 5000 metres gold medals at the European Championships in Moscow. At the Olympics, he missed the medal places, finishing 5th and 6th in the K-1 1000 metres and K-4 1000 metres finals, respectively. The following year in July, he defended his European K-1 1000 metres title in Plovdiv, but lost the K-1 5000 metres crown to his German rival Max Hoff. However, the following month, Pimenta would beat Hoff in a sprint finish for the K-1 5000 metres gold medal at the World Championships in Račice, to win his first individual world title. On 5 March 2018, he moved from Clube Náutico de Ponte de Lima to S.L. Benfica.
