Green, who scored the opening goal for the U`s in their play-off final triumph over York at Wembley last May, has made 21 appearances for Town`s near neighbours this term, 12 of which have been starts, and scored two goals.
Robins boss Mark Yates told Cheltenham`s official website: "I`m thankful to Chris Wilder and Oxford for allowing Matt to come here.
"He is an out-and-out striker with a natural ability to score. He`s quick, strong and he will add a lot to this squad.
"I was interested in a couple of Chris` players and I was always hoping we could do something with Matt after we had played them at the weekend."
Green was not included in Oxford`s matchday 18 on Saturday as the two sides played out a 1-1 draw at the Kassam Stadium.
Source: PA
Source: PA