Gajewski played for the Polish team in the Chess Olympiads of 2008 in Dresden, where he played on the fourth board scoring 6½ points from 10 games, and 2014 in Tromsø.[5] He also took part in the European Team Chess Championship in 2007, 2009, 2013 and 2015; Gajewski won the individual silver medal on board three in 2007.[6]
Since the pandemic, he has been working with some of India's sharpest chess players at Westbridge Anand Chess Academy (WACA). Since 2023, he has been working as Gukesh Dommaraju's second, assisting him in winning the 2024 Candidates Tournament, where Gukesh became the youngest challenger in the history of the World Chess Championship.[9] He was also Gukesh's main trainer when he won the 2024 FIDE World Chess Championship against Ding Liren.