The Belgian striker has recently rejected a new deal from the Toffees and has been strongly linked with a summer move to the Blues.
However, Keown reckons that the 23-year-old will struggle for playing time in Antonio Conte's side.
"He's not going to get a game though is he," he said on BT Sport.
"Costa will play."
Lukaku has made it clear that he wants his future to be away from Goodison Park, which means speculation surrounding his transfer will only continue roll in over the next few months.