On Friday, German outlet Ruhr Nachrichten S04 reported that the Cameroonian opted to end after being released by Liverpool.
The Premier League club confirmed the news on Saturday via social media.
Matip, who came through the ranks at Schalke, suffered a ruptured cruciate ligament in December 2023 and was forced to miss the entire second half of last season under Jurgen Klopp.
When his spell at Liverpool, which ran since 2016, came to an end, the experienced defender was in the sights of several clubs, who saw him as a shrewd investment.
In recent months, the Cameroonian had been approached by several Italian clubs - including Juventus and Roma - as well as former club Schalke.
There were seemingly many alternatives for Matip, but, despite the possibility of competing at a high level, he's decided to hang up his boots.
Matip won the Premier League, Champions League, Super Cup, Club World Cup, FA Cup, Community Shield and two EFL Cups with Liverpool.
He also won the DFL-Supercup and DFB-Pokal in Germany.