Marie Jones' smash hit play Stones In His Pockets is being given the silver screen treatment.
Keating (36) will play the part of Jake Quinn, while Game of Thrones star Hill will reprise his original role of Charlie Conlon, which won him an Olivier Award for Best Actor in 2001.
The story centres on Jake Quinn and Charlie Conlon, who are employed as extras in the movie.
The key point in the play is when a local teenager commits suicide after he is humiliated by one of the female stars of the film. He drowns himself with stones in his pockets, devastating the town.
Belfast playwright Jones saw her show premiere at the West Belfast Festival in August 1996, before going on to tour Ireland where audiences fell in love with the production which uses just the two main actors.
The original cast of Conleth Hill and Sean Campion then took the show to Broadway and the West End where it played to packed houses and gathered up countless awards.
It picked up three prestigious Tony Award nominations in New York.
Jones has also been involved in plans to turn her smash hit stage show into a movie.
Her casting agent Ros Hubbard – who worked on The Commitments, Into The West and Bloody Sunday – contacted Keating after Jones saw him being interviewed by Piers Morgan on his TV show when Keating was seen to break down over his marriage split.
Speaking to RTE, Jones said: "I started to listen to him.
"The camera really loved him. He had so much controlled emotion and was dead honest.
"I thought 'he'd be brilliant in Stones, why isn't he an actor?'. He said he wanted to do more films."
Hubbard contacted Keating, who said he was interested and did a screen test.
Stones marks Keating's second acting role. Earlier this year he starred in an Australian movie called Goddess opposite actress Laura Michelle Kelly.
Several well-known actresses are in the pipeline to play the role of the film star who humiliates the local teen.
Jones is adapting Stones herself for the big screen and her husband, Ian McElhinney, will reprise his role of director.
It is understood filming will get under way next year and that it will use a number of locations.
These are expected to be in various places both north and south of the Irish border.
The movie is expected to cost £2.5m to make.
Funding applications have already been lodged with both Northern Ireland Screen and the Irish Film Board.
Jones said she was initially reluctant to adapt the play for the big movie screen.
However, she is now said to be "very excited" about the project.
Stones In His Pockets was written by Belfast playwright Marie Jones in 1996 and premiered at the West Belfast Festival and played The Lyric.
It then went on to the Edinburgh Fringe, London's West End, The Tricycle Theatre, and Broadway, picking up rave reviews and awards:
* The Irish Theatre Award for Best Production.
* Evening Standard Award, Best New Comedy.
* Two Olivier Awards for Best New Comedy and Best Actor.
* Sean Campion was also nominated for an Olivier for Best Actor.
* Drama Desk, Special Award.
* Three Tony nominations.