The 24-year-old joins the club on an initial two-month loan from League Two side Barnet.
Galvin, who operates as a left-sided defender, is eager to help towards the start to the season.
“I’m delighted to be here”, says Ryan.
“I’ve had conversations with the gaffer and he’s told me how he sees me playing.
“I’ve played the last two seasons in this league and got to the playoffs twice, so hopefully I can come to Rochdale, go all the way and get promoted.
“The club are flying high, winning games, it’s a good team to come into and hopefully make an impact.”
Galvin came through the ranks at Wigan Athletic which included a stint at Stafford Rangers in late 2019.
Following departure from the Latics, Ryan joined Sheffield Wednesday after an initial trial in 2020, making his debut in an FA Cup tie at Exeter City. Successful loan spells at Gloucester City and Maidstone United followed, as he claimed player of the month in his first full month at the Stones.
In June 2023, FC Halifax Town captured his signature, going on to spend two seasons at the Shaymen, making over 70 appearances in back-to-back playoff finishes.
Galvin had been on Dean Brennan’s radar for 18 months and after the Bees’ promotion to the EFL, he made the move down south. His debut came in an EFL Cup tie at home to Newport County in July, netting the first of two late goals.
The defender will wear the number 37 during his stay at the Crown Oil Arena.
Welcome, Ryan!
The loan deal is subject to National League and FA approval.