Andre Villas-Boas was confirmed on Wednesday as the new manager of Premier League club Chelsea, DPA reported.
Villas-Boas, 33, has signed a three-year contract and replaced Carlo Ancelotti, who was sacked shortly after the final game of last season, having failed to add any silverware to the double he had won the year before.
"Andre was the outstanding candidate for the job. He is one of the most talented young managers in football on Wednesday and has already achieved much in a relatively short space of time," said a statement on the Chelsea website.
Villas-Boas, whose grandmother was from Northumberland in the north-east of England, speaks fluent English and worked as an assistant to Jose Mourinho at Chelsea.
He has emerged as one of the brightest young managerial talents in Europe, having won the treble of league, Cup and Europa League with Porto last season.
"His ambition, drive and determination matches that of Chelsea and we are confident Andre's leadership of the team will result in greater successes in major domestic and European competitions," the Chelsea statement went on.
"Andre will bring his coaching experience back to a club he is already very familiar with, having previously worked here for three years.
"He has always been highly regarded at Chelsea and everyone here looks forward to welcoming him back and working with him."
Villas-Boas's release clause of 15 million Euros (21.5 million dollars) at Porto was met on Tuesday as he filed his resignation. It is believed he will sign a salary with 4.4million pounds a year.