Philliskirk, 22, son of Latics academy boss Tony, has yet to appear for Lee Johnson's side but was an unused substitute in last weekend's home win over Port Vale.
Johnson told the club's official website: "Danny has done really well since he arrived. He is technically very good and an excellent finisher.
"He needs to become a man in his personality on the pitch and, if we can get that into his game, he can become a top player and back to where he was as a youngster.
"Danny provides us with another attacking option - we have lots of them - and I believe this side will score goals whoever plays up front."
Philliskirk began as a trainee at Oldham before spending four years at Chelsea and moved on to Sheffield United, initially on loan, in August 2011.
He made only four league appearances as substitute for the Blades and in February joined Coventry where he made one league appearance.