The Congolese winger will continue his spell in Germany after committing his future to the Bundesliga side, although the exact terms of the new deal have not been disclosed.
Despite suffering a serious injury, a fractured tibia and fibula during a UEFA Champions League round of 16 fixture, the African continues to enjoy the full confidence of Mainz.
Following the announcement, the 24-year-old expressed his gratitude, thanking Mainz for their continued support during his rehabilitation and reaffirming his commitment to the team.
“I am very grateful to the management of Mainz 05 for their unwavering support,” Katompa said.
“My main aim now is to do everything I can to get back on the pitch as soon as possible. I am determined to prove that the trust placed in me is well-founded.”