Cho becomes the Tigers' 12th signing of the summer on a five-year contract, joining for a fee reported at around €15m, a deal that could rise further with add-ons tied to Hull City's Premier League survival.
The 22-year-old previously spent time at Real Sociedad before rebuilding his reputation at Nice, where he established himself as a regular over the past two and a half seasons.
"I'm really excited. I'm very happy to be here and looking forward to helping the team as soon as possible," Cho said.
"Coming back to the UK is a really positive point, and then the experience of playing in the Premier League. I'm excited to experience this league — it's the best league in the world.
"It's going to be a really good challenge."
Cho pointed to existing connections at the club as part of what made the move appealing.
"It was a good experience in France. I spent a good few years at Nice, played in Europe and really enjoyed it. I'm really happy to be back in the UK now and close to my family," he said.
"My friend Nobel Mendy scored [against Manchester United] and I was really happy for him and the club. I know Darko [Gyabi] from the England youth team and Lucas [Gourna] from back in Paris. I'm an attacker and can play all three [forward] positions.
"My main qualities are dribbling, speed, taking risks and taking on players. I can't wait to get to know the fans, play in front of them and hopefully get good results, help the team and score goals."
Hull City's business at the top end of the pitch isn't finished there. Vaz is closing in on a temporary switch from Roma, with the structure of the proposed deal — a €2m season-long loan carrying a €30m option — designed to give both sides room to assess whether a permanent transfer makes sense next summer.
Vaz joined AS Roma from Marseille in January for a fee reported at around €22m-25m, having scored four goals in 14 Ligue 1 appearances in the first half of that season. He featured 12 times off the bench in Serie A for the Italian club, scoring once, but has struggled for regular minutes under Gian Piero Gasperini.
Vaz previously played for Ligue 2 side Sochaux before his move to Marseille in 2024 and has represented France up to under-20 level, giving Hull a young, high-upside option to complement Cho's more experienced profile in attack.