The veteran goalkeeper’s sole appearance for the club came in a 2-1 friendly loss to Sevilla, making the substitutes’ bench on eight occasions in the campaign proper but failing to make it onto the pitch.
With his contract up, he went on to play for both Stoke and West Brom – albeit with only one appearance between the two spells combined – before heading into the summer as a free agent.
Everton have now moved to bring the 37-year-old in as cover following an injury to academy goalkeeper Harry Tyrer, as Benitez revealed on Friday.
“He’s a player I think can give us some experience, because we need it to sort out this problem just in case,” he told reporters.
“So we have a new signing, but it’s a player maybe nobody was expecting!”
Lonergan’s move to Goodison comes after the controversial appointment of an ex-Liverpool manager in Benitez, with the ‘keeper joining a small list of double agents between the two Merseyside rivals.
The likes of Peter Beardsey, Nick Barmby, Abel Xavier, Sander Westerveld, Steve McMahon, Gary Ablett, David Burrows and Kevin Sheedy have featured for both clubs, with Westerveld the most recent in 2006.
It is unlikely that Lonergan will make a competitive appearance for Everton during his time with the club, but his move across Stanley Park is certainly an intriguing one.