It was current Bluebirds manager Ady Pennock who signed the 28-year-old for the Gills in August when he was in charge at the Priestfield Stadium.
And now he re-unites with the keeper for a third time, having also worked with him at Forest Green Rovers.
Arnold made two appearances for the Gills after signing a one-year deal in August. Both of those came in the Checkatrade Trophy, impressing at home against Southend United before keeping a clean sheet against Colchester in October.
He also featured in the penalty shoot-out victory against Phoenix Sports in the Kent Senior Cup.
He joined the Gills from Dover Athletic where he had made thirty National League appearances last season, keeping nine clean sheets.
Originally with the youth sides at Boreham Wood and Arsenal, Arnold then turned pro with Norwich City in 2007 but left in May 2008 without making the senior side.
He had spells with Grays Athletic, Eastleigh, Wycombe Wanderers and Stevenage Borough before signing for Forest Green in June 2014.
He helped Forest Green to the 2015/16 National League Promotion Final at Wembley, only to lose 3–1 against Grimsby Town.
The next day it was confirmed he had been offered a new contract by the club. However, less than a month later, they announced they had released him and he subsequently joined Dover.
Meanwhile, Barrow have announced that club Director Ian Rainford has stepped down from his role at the club after several years of service.
Rainford has been a volunteer at the club for many years, even as far back as 1999 when he was part of the survival fund, helping to secure the clubs future at Holker Street at one of the clubs lowest times.
He was appointed as a director in December 2015 and has worked in a fans liaison role since, taking fans concerns and bridging the gap between the supporters and the board. His efforts have been greatly appreciated by the club and supporters alike over the years.
He was also part of the Bluebirds Trust, working with their initial steering group at their formation in 2014, and has worked with various supporters` groups to drive forward projects, including the ground maintenance team.