Santos completed a move to Chelsea from Vasco da Gama last January, before he returned to the Brazilian club in March on a loan deal until June.
After linking up with Mauricio Pochettino's side ahead of the 2023-24 campaign, Santos was sent on loan to fell Premier League club, Nottingham Forest.
While the plan was for Santos to spend the whole campaign with the East Midlands club, Chelsea exercised their right to recall him earlier this month.
The 19-year-old struggled to make an impact at the City Ground, making just one start in the EFL Cup and playing just seven minutes in the Premier League.
With the Blues keen for Santos to play regular game time, they have decided to send him on loan to their sister club Strasbourg.
Like Chelsea, the Ligue 1 side are owned by BlueCo, which is a consortium led by Todd Boehly and Clearlake Capital.
Santos will spend the rest of the season in France, before he returns to Chelsea in the summer, with no buy option included in the loan deal.
In a statement, Chelsea said: "Chelsea midfielder Andrey Santos has joined French club Strasbourg on loan until the end of the season.
"The 19-year-old spent the first half of the campaign at Nottingham Forest and will now continue his development in Ligue 1.
According to journalist Eduardo Burgos, Strasbourg boss Patrick Vieira was a crucial factor behind the decision to send Santos on loan to the French club.
The report claims that Chelsea turned down loan offers from two Premier League clubs and three Championship teams.
Santos will link up with his new teammates after he completes his stint with Brazil Under-23s at the Pre-Olympic tournament in Venezuela.