Sarr joined Porto on loan from Chelsea last year in order to gain regular first-team action.
But the 22-year-old French star has endured a mixed spell at Porto, playing just 14 matches in the starting XI and five substitute appearances across all competitions for the Portugal giants.
However, neither Porto nor Sarr have any desire to turn the loan agreement into a permanent deal.
Sarr will now return to Chelsea in the summer after his loan spell at Porto expires.
He joined Chelsea from French Ligue 1 side, Nice last summer transfer window.
Sarr will hope to break into Thomas Tuchel’s first team at Stamford Bridge next season.