The Irishman will join officially on July 1st after his contract at Aston Villa expires and O'Holloran told Sky Blue Player: "I'm delighted to get a deal done.
"I had a meeting with the manager earlier in the week and he was very positive. I got a great vibe from him.
"He said he saw me play last season in the reserves and that he liked what he saw which was great for me."
He did not play as many games for Villa as he should have done due to a knee injury, but Holloran said: "I suffered a knee injury but Villa have been looking after me very well.
"I'm just looking forward to playing next season but first I want to get a good pre-season under my belt. I've already started doing some fitness work over the post season to make sure I keep myself in shape so now I'm looking forward to getting with the squad and meeting all of the lads.
He did not play as many games for Villa as he should have done due to a knee injury, but Holloran said: "I suffered a knee injury but Villa have been looking after me very well.
"I'm just looking forward to playing next season but first I want to get a good pre-season under my belt. I've already started doing some fitness work over the post season to make sure I keep myself in shape so now I'm looking forward to getting with the squad and meeting all of the lads.
"I'm a good player despite my injury and here on in I'm only going to get stronger."