Eliaquim Mangala has joined Valencia on a two-year deal, having spent the 2016-17 season on loan at the LaLiga club from Manchester City.
The financial terms of the transfer have not been disclosed.
A brief statement issued by Valencia read: "Valencia CF has reached an agreement with Eliaquim Mangala, whereby the French defender will become a Valencian player until June 30, 2021."
Valencia begin their LaLiga campaign at home to Real Sociedad on Saturday.
Mangala joined City from Porto in August 2014 in a deal worth in the region of £42 million (A$62 million), only for a succession of error-strewn displays to prevent him from becoming a regular first-team fixture under Manuel Pellegrini.
The 28-year-old returns to Mestalla, where he spent the 2016-17 campaign on loan before an unlikely and brief first-team return during Pep Guardiola's second season in charge at City.
His proposed move to Crystal Palace collapsed before injuries to John Stones and Vincent Kompany contributed to him making 15 appearances in all competitions during the first half of 2017-18.
A January loan move to Everton followed, which was ruined by a serious knee ligament injury in his second match.
Mangala did not feature for City as he underwent his recovery but signed a one-year contract extension until June 2020 in March this year.