Liverpool confirmed last night they had agreed a fee with Portsmouth and personal terms with Johnson, 24, following a three-way chase for his signature.
But the right-back, who has revived his career on the south coast, has chosen to move to Anfield and join last season’s Premier League runners-up.
But with Reds manager Rafael Benitez working on a restricted budget, Johnson’s arrival is likely to trigger defensive departures.
Italian full-back Andrea Dossena is the most likely to leave. The 27-year-old has struggled to make an impact on Merseyside since arriving from Udinese for £7m last year, and has been linked with a move back to his homeland. Spain defender Alvaro Arbeloa is another who could be sold. The 26-year-old, who can play anywhere across the back four, is reported to be a target for Real Madrid.
Johnson had hinted that he would not favour a return to Chelsea, where his early promise stagnated after joining for £6m from West Ham as an 18-year-old. He moved to Portsmouth, initially on loan, and rediscovered his best form, forcing his way back into the England team.