The Italian has joined the relegation candidates on a five-year contract, subject to a work permit.
Speaking to the Tottenham Hotspur media, Roberto De Zerbi said: "I am delighted to be joining this fantastic football club, which is one of the biggest and most prestigious in the world.
“In all my discussions with the club’s leadership, their ambition for the future has been clear – to build a team capable of reaching great achievements, and to do that playing a style of football that excites and inspires our supporters.
"I am here because I believe in that ambition and have signed a long-term contract to give everything to deliver it.
“Our short-term priority is to climb the Premier League table, which will be the complete focus until the final whistle of the last game of the season.
"I’m looking forward to getting out on the training pitch and working with these players to achieve that.”
Roberto managed Brighton to the Europa League during a two-year Premier League spell.
On his departure from the south coast of England, he'd said: "I am very sad to be leaving Brighton...
"But I am very proud of what my players and staff have achieved with the support of everyone at the club and our amazing fans in the past two historical seasons".
After that he achieved a runner-up finish with Marseille in the 2024/25 season, leaving the French side this February.