Irish announced that lock Skivington's new deal will see him remain with the Exiles until 2016.
Skivington, 30, joined Irish from Leicester last summer. Prior to his spell with the Tigers, he spent eight seasons at Wasps.
"George has been enormous for us this season," Irish rugby director Brian Smith said.
"He's had a huge impact in many of our big wins, leading from the front and setting a great example for the rest of the pack.
"His commitment to the club for the next three seasons gives us another key player to build our new team around."
Skivington will skipper Irish in Saturday's Premiership clash against Madejski Stadium visitors Worcester.
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