The former France Under-21 international has joined the Magpies on a five-year deal after failing to establish himself as a Manchester United regular in two seasons at Old Trafford.
“Gabriel is a player I’ve watched for the last couple of seasons since he arrived at Manchester United,” Newcastle boss Alan Pardew said.
“He has great pace and excellent technique and he has improved his power in the last 12 months and is ready now to make a real impact in the Premier League,” he added.
Obertan’s signing makes the 22-year-old the fifth French-born player to arrive at St James Park this summer following the signings of Yohan Cabaye, Demba Ba, Sylvain Marveaux and Mehdi Abeid.
Meanwhile, Tottenham’s South African international Steven Pienaar will miss the first six weeks of the Premier League season after suffering a groin injury, the club said Tuesday.
Pienaar, 29, picked up the injury during Spurs’ pre-season friendly against Athletic Bilbao on Saturday, and underwent surgery early Tuesday.
“Following scans and consultation with an independent groin specialist, Steven Pienaar underwent groin surgery this morning,” Tottenham announced on the club’s official website.
“(He) is expected to be sidelined with the injury for up to six weeks.”
Pienaar joined Spurs from Everton in January on a four-year contract.