The Red Army dominated for most of the game and secured victory thanks to a man of the match performance from Paul O’Connell and two tries from New Zealand born Kerryman Danny Barnes.
It was a game Munster dominated and could have won even more comfortably.
Ronan O’Gara put Munster in front after 14 minutes with a penalty straight in front of the Ballynanty end.
The first try came in the 32nd minute, Danny Barnes was released on the wing after 14 phases, completing a long period of sustained pressure.
O’Gara failed to convert and it was 8-3 at half-time following a 37th minute penalty from Dan Biggar.
Ospreys replacement hooker Richard Hibbard was sin binned in the 49th minute.
O’Gara converted the resulting penalty making it 11-3.
Biggar made it 11-6 on 55 minutes, when Munster were penalised for coming off their feet.
Two minutes later Danny Barnes grabbed a superb individual try, when he blocked a Richard Fussell clearance five metres from the line and ran in under the posts.
The Kerry Kiwi was given a standing ovation when he was replaced by Simon Zebo.
O’Gara converted to make it 18-6.
Ospreys were rewarded for their efforts when Richard Fussell went in the 78th minute.
It was too late for Ospreys as Munster sealed a Magners League Grand Final spot on the Saturday May 28.