The midfielder had made the switch to Rangers at the start of the season, but having not settled in Scotland, his temporary deal was terminated early.
Ejaria initially impressed under Steven Gerrard, but found himself receiving less game-time after struggling to adapt to life in Glasgow.
The midfielder made 28 appearances under Gerrard before requesting an early return to Anfield and has been training with the U23s since.
The 21-year-old has now completed a second loan deal of the season, with new Reading manager Jose Gomes drafting him in with his side sitting in 23rd place in the Championship.
Ejaria still has another two years and a half years left on his contract and, despite being rated highly, is expected to leave the club due to competition for places in the first-team.
He has made eight appearances for the Reds under Jurgen Klopp, all in the 2016-17 season.