The Irishman, who has one international cap, was a key figure last season following his free transfer move from Sunderland.
He claimed the Golden Glove award with 24 clean sheets as the Iron won the League One title, and is delighted to pen a two-year deal to stay put.
"It is great to sign it and I'm looking forward to the start of the season," he said.
The 25-year-old would have been out-of-contract at the end of this campaign.