The 22-year-old signed a six-year contract at Newcastle, and he’ll be wearing the No 10 shirt next season.
Bruce said: “I’m delighted to bring Allan to St. James’ Park. He is a very talented young player with a big future ahead of him.
“He has all the attributes you would want in an attacking player, including lightning pace, so I’m sure he’ll excite everybody.
“He is a great addition to Newcastle United and the Premier League.”
Saint-Maximin is largely a right-sided attacking forward, but has also been known to play on the left, or down the middle as a centre-forward.
He made 34 appearances in Ligue 1 for Nice last season, scoring six goals and recording five assists.
Meanwhile, Newcastle confirmed their fourth signing of the summer within an hour before announcing Saint-Maximin.
The club signed 25-year-old left-back joined the Magpies on a one-year loan deal from Eintracht Frankfurt.
Newcastle also have the option to make the move permanent at the end of the loan spell.
Bruce said: “Jetro brings a wealth of experience into the dressing room and I’m very pleased to have brought him here.
“He has played at the highest level and is naturally left-footed so he’ll give us another strong option on that side.”
Newcastle have also spent a club-record £40m on Hoffenheim striker Joelinton this summer, as well as bringing in midfielder Kyle Scott and goalkeeper Jake Turner on free transfers.
