The 24-year-old has played just seven minutes after joining the Light Blues from National League side Barrow in the 2019 January transfer window as he’s mostly played third-stringer behind Allan McGregor and Jon McLaughlin.
However, Firth insists he’s learned so much from playing behind the two Scottish internationals and wasn’t deterred by McGregor’s decision to continue playing for another campaign.
He told the Rangers website after signing the contract: “Everyone knows how much I love being here. It has been a really special year for us and I am just happy that I can stay here for next season.
“It has been brilliant for me being here and to get the chance to work with Greegsy, he is incredible and to work alongside Jon is great. For me to pick the brains of people who have been there at all different levels and to have Colin Stewart to work with is perfect.
“I have had game time in the B-Team to keep myself fresh but the work in training has been massive for me.
"The fact I am not playing has given me a chance to work on things you sometimes don't get to work on when you are playing so it has definitely helped me a lot and I feel like I am in a good place and hopefully it will continue.”
Firth is a former Liverpool club-mate of manager Steven Gerrard having come through the youth ranks at Anfield.