The 18-year-old striker joined the St. Mary's Stadium outfit in 2016 after being offered a two-year scholarship contract and, last season, starred for the Saints' U18 and U23 sides, thus competing in the English Premier League 2 Division 2.
He made 27 appearances in all competitions [including two Football League Trophy games for the U21s] and scored eight goals, laying four others to grateful teammates.
And the reward for his efforts was a pro deal, with the striker looking to emulate, to name a few, the likes of James Ward-Prowse, Alex Oxlade-Chamberlain and Luke Shaw; all of whom rose through the ranks of the famed Southampton youth system to feature prominently for the first team, and have become English Premier League stars.
"I'm delighted to sign my professional deal at Southampton Football Club. It's a great club to be at, great facility and they have a great philosophy," Afolabi told Goal.
"Down the years, many youngsters have gone through the system and gotten to the first team so we are here, everyone probably hoping to follow in their footsteps."
On his target for the upcoming season, the left-footed striker - whose pace and silky feet makes him adept at playing on the flanks - would not mind helping out, in the first team, out wide.
"My target this season would be to cement a place in the U23 team and get goals as much as possible and then try and showcase myself in the first team," he continued.
"I'll be willing to play down the middle - as a centre-forward.
"In the middle; that's where I feel I can show all my talent and all my traits. But if I was asked to play out wide, I won't mind either because I'll be willing to play in a more disciplined role for the team and I'd be glad to help in any way I can."
On the international scene, Dublin-born Afolabi - who has reportedly been on Chelsea radar since 12 - is a consistent fixture for Ireland U19s but is very much eligible to turn out for his parents' country, Nigeria.