The 22-year-old joins the Gills on loan for the remainder of the season and becomes manager Steve Evans’ first signing of the January transfer window.
He joins fellow Saint Tom O’Connor on loan at Priestfield and follows in the footsteps of Alfie Jones from last season - continuing the positive working relationship between Gillingham and Southampton.
Evans has expressed his desire to make the move permanent, too.
He has been assigned squad number 17, and is available for selection for the Gills’ weekend game against Burton Albion.
He made his Premier League debut in a 3-2 win over Arsenal in December 2018, and has also spent time on loan at National League Woking and USL side Hartford Athletic, where he scored two goals in 15 games.
What it means
Gillingham have been crying out for a left-sided midfielder all season, and now they have one.
It seems manager Steve Evans’ preferred formation is 442, and he has often had to shoe-horn players into the left midfield role, but now he has a natural fit at his disposal.
Gillingham fans can expect to see a lot of Johnson between now and the end of the season, and potentially beyond.
Steve Evans told Gillingham’s website: “We are delighted to have signed Ty on loan. He is an exciting prospect and I have no doubt he will fit in well with our current group.
“He is very quick, direct, hungry, and will cause defences a lot of problems in our division."
He also added: “Our intention is to make this deal permanent which will give us more flexibility in the loan market over the next few weeks.”