The 24-year-old Netherlands midfielder, who signed for Chelsea in 2013, has extended his deal by a year to 2019.
He helped PSV win the Dutch title while on loan during the second half of the 2015-16 campaign and will now return to Eindhoven until the end of this season.
In recent months he has had treatment for a recurring knee injury but said he is "now ready for top football".
"Rest and physiotherapy were necessary," Van Ginkel said.
Van Ginkel has played four competitive matches for Chelsea since originally joining for £8m from Vitesse Arnhem.
He was loaned to Stoke at the start of the 2015-16 season, playing 21 times, before moving to PSV, where he scored eight times in 16 appearances.
This season, Phillip Cocu's side sit third in the Eredivisie, eight points behind leaders Feyenoord.
Marco van Ginkel has extended his contract with Chelsea - and rejoined PSV Eindhoven on loan on the same day.