The 22-year-old moves to Oakwell seeking more regular game time after featuring just twice from the bench in ten Premier League appearances for Wolves this season.
Chirewa, who joined Wolves from Ipswich Town in 2023, has also enjoyed previous loan spells at Derby County and Huddersfield Town. He believes Barnsley offers the perfect opportunity to make an impact in League One and showcase his talent.
"I'm at a stage in my career where I have a point to prove," he said on the club's website as quoted by BBC.
"I want to show what I can do and really influence games. The manager's vision for the club convinced me this is the right place to take the next step."
The winger is Barnsley's fifth signing of the January transfer window, following permanent deals for Charlie Lennon and free-agent Eoghan O'Connell, as well as loan arrivals Owen Goodman and Scott Banks.
Manager Conor Hourihane is optimistic that Chirewa's top-level experience and versatility will provide a vital boost.
"He brings Premier League exposure and can play across the front line," Hourihane said.
"That gives us another dimension as we approach the final stretch of the season."
Currently 15th in League One, Barnsley have won just once in their last seven matches. Chirewa's arrival could provide the spark the Tykes need to climb the table and finish the season strongly.