Ejaria is a product of Arsenal's youth system where he failed to make the grade but the Reds were more than happy to snap him up, away from the clutches of Manchester United who were also interested in the youngster. The left-footed central midfielder went on trial at Liverpool as part of their Under-17 side that reached the final of the 2014 Aegon Futures Cup in the Netherlands. He clearly impressed and was part Liverpool's 2016/17 pre-season tour in the States and on the bench at Stamford Bridge in a 2-1 win over Chelsea in the Premier League on 16 September 2016. His first competitive appearance was against Derby in in a League Cup tie on 20 September 2016, when he came on as a substitute with ten minutes remaining. Ejaria went on to make two Premier League substitute appearances and also played in all three of that seasons FA Cup games.

In the summer of 2017 Ejaria was part of England's under-20 World Championship winning squad. After failing to make any of the matchday squads in the first half of 2017/18, he joined Championship strugglers Sunderland on loan on 31 January 2018. In the summer he signed a new long term contract and was loaned to Rangers for 2018/19. However, after two goals in 28 appearances the spell was cut short on 15 December and Ejaria returned to train with Liverpool. On 7 January 2019, it was confirmed that Ejaria would spend the rest of the season on loan with Championship strugglers Reading, where he scored once in sixteen appearances. On 8 August 2019 a further loan deal with Reading was agreed for the whole of the 2019/20 season with the Berkshire club having an obligation to buy at the end of it which they did for £3.5 million on 28 August 2020.