Davis previously played for the club from 2008-12, winning eight trophies including three league titles during his stay.
The midfielder scored 22 goals in 210 appearances for the club before moving to Southampton, where he proved a mainstay, making at least 25 appearances in each full season.
However, this campaign, Davis has fallen out of favour, playing just six times under managers Mark Hughes and Ralph Hasenhuttl.
Davis' loan was made official on Sunday, giving the midfielder a chance at first-team action as Rangers push for a league crown once again.
“I’m delighted to be back and looking forward to getting started. It’s been a little while in the making but when I found out the club was interested, this is the one that I wanted to happen," Davis told RangersTV in Tenerife, where he joined up with the team for training.
“I found out there was interest a little while back and talks were ongoing between the two clubs to try and come to a conclusion. And then, when the decision is made, it all happens very quickly; so obviously I’m delighted to get it agreed last night and I was straight on the flight this morning to get out here.
"It’s great to be back and I am obviously very familiar with the club. I’m sure there will be plenty of faces I recognise as I go along and I’m looking forward to getting back out at Ibrox.”
Davis isn't the only big name to join up this window as former England star Jermain Defoe has also been added by his former Three Lions team-mate Gerrard.
Playing under Gerrard was one of the major draws for Davis, who is looking forward to learning from the former Liverpool star.
“He is an icon for any young player coming up and likewise for myself as well. I’m sure I’ll learn a lot from him and he’s obviously done a fantastic job in the six months he has been here," he said.
“There seems to be a real good camaraderie within the squad and I’m looking forward to getting to know the boys a bit more this week.
“It’s a good introduction for me as well and then we’ll get back to Scotland and start the games.
"I think the club has come a long way in the last couple of years. Obviously the Old Firm result was massive for everybody and it was a massive psychological boost for the boys as well.
“So it’s a great time to come in amongst it. I’m just raring to go and can’t wait to get out there.”
Rangers currently sit tied with Celtic on 42 points, although the Ibrox side have played one more game than their rivals.