The defender, who captains both Scotland's Under-15 and Under-16 sides, made four appearances for Celtic B last season before opting to make the move south.
He has signed a five-year contract at Anfield, having rejected an offer to extend his stay in Glasgow, with Liverpool having tracked the youngster since the turn of the year before finally getting the deal over the line.
Jikiemi's arrival continues a busy period of investment in young central defenders at Liverpool, following the additions of Jeremy Jacquet and Giovanni Leoni to the first-team picture, plus academy signings including Mor Talla Ndiaye and Ifeanyi Ndukwe.
He becomes the fifth young centre-back to join the club since last summer. He is regarded as a modern defender, comfortable playing out from the back and looking to break lines with his passing, and is seen as one of the brightest prospects to emerge from Celtic's academy in recent years.
The move comes during a summer of significant change at Liverpool, who finished fifth in the Premier League last season and will play Champions League football in 2026-27. The club parted ways with head coach Arne Slot after the campaign, with Andoni Iraola brought in as his replacement, while centre-back Ibrahima Konaté departed for Real Madrid.
For Celtic, the exit represents another blow at academy level, echoing the earlier departure of Ben Doak, who made a similar switch to Liverpool as a teenager before going on to impress at Anfield and later securing a permanent move to Bournemouth.
Losing promising players before they break into the first team remains a persistent challenge for the Scottish champions whenever Premier League clubs come calling, though the compensation received in such deals typically softens the blow financially even if the football cost is harder to swallow.