Murray has spent his entire professional career with the Munstermen, who have not lost in the RaboDirect PRO12 since September.
They sit on top of the pile, as well as leading their Heineken Cup pool, and O'Mahony is pleased to see the good news keeps coming.
"Thrilled to bits, really," he told the Irish Examiner. "He's obviously a very close friend of mine so it's going to be great to have him around for two more years.
"He's (been) a hugely important part of our team over the last few years, now he's a Lion and an established international so he's a hugely important part of the cog of Munster so it's great to have him sign on again.
"He's one of the best scrum-halves in the world. It's great to be playing alongside him and as I said, he's a hugely important part of the team and I'm delighted that he's staying at home.
"Knowledge-wise, he's the man to go to about detail. He drives that side of things for us. From where he's come from, he's got a massive, massive amount of experience."
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