He has become the latest player to secure an EFL move after Northampton Town came calling.
The 31-year-old kept 27 clean sheets last season, forming part of a defence that conceded only 30 National League North goals as they won promotion via the play-offs.
Andy Butler, who has today signed Joey Dawson following his departure from Scottish Premier League side Celtic, has suffered the blow of losing Fitzsimons and knows he has big gloves to fill.
The keeper said on social media: "It's with deep sadness that the time has come to say goodbye.
"But it will never be the end as individually and collectively as a group we will be part of the club's history together.
"All I wish is that whoever is lucky enough to wear that no1 shirt next season, the fans sing his name in the same manner you did mine."
The club wanted him to stay and a statement on the official website read: “Following the conclusion of the end of the season, Scunthorpe United did enter negotiations with Ross and offer him a new deal but remained realistic with the fact he had a large amount of interest, and his desire to take an opportunity in the EFL was one all too good for him to turn down.
“Everyone at Scunthorpe United would like to thank Ross for his efforts while with the club, and wish him all the very best for the future.”
Northampton manager Kevin Nolan is thrilled with his capture.
“His performances last season were fantastic, he broke all sorts of records and picked up the Goalkeeper of the Year Award at the National Game Awards which says all you need to know about how well he did and he deserves this opportunity," he said.