Brendan Rodgers hailed Odsonne Edouard as one of the best young prospects in Europe after Celtic broke their transfer record to land the French player on a permanent deal.
The Hoops are reported to have splashed out £9m to secure the 20-year-old Frenchman on a four-year contract from Paris St Germain.
Edouard netted 11 goals in 29 appearances last season - including three netted against Rangers - as the Parkhead outfit secured their second straight domestic treble.
And despite the competition from Moussa Dembele and Leigh Griffiths, manager Rodgers believes the vast sum Celtic have paid for Edouard's services is money well spent.
He told the club's website: "We are delighted to make such an important signing. Odsonne is one of the best young players I have worked with and one of the best in Europe.
"Our fans saw exactly what he is capable of last season and we look forward to working with him again as we look to build on the tremendous success we achieved last year. I am sure he will be a big player again for us this season."
Celtic called the signing the "biggest transfer" in their history but did not disclose the fee paid. Their previous record stood at the £6million paid for strikers John Hartson and Chris Sutton.
Edouard struck a debut goal against Hamilton back in September but really made his mark against Rangers at Ibrox as the 10-man Hoops pulled off a stunning 3-2 victory at the home of their bitter rivals.
He then went one better with an Old Firm double on the day his side wrapped up their seventh straight league crown with a 5-0 win over the Light Blues.
"From the moment I walked into Celtic, the club has felt like home to me," said Edouard. "I have been made to feel so welcome by everyone at the club and our fans have given me such brilliant support.
"Celtic is one of the world's great football clubs and I was desperate to make my move permanent. The scenes from May when we achieved such a historic double treble and made the city come alive are still very fresh in our memories.
"To see our fans so happy is the reason you play football and now we want to do everything we can to bring our great supporters even more success."
Celtic chief executive Peter Lawwell had been in talks with the Parisians since the end of the season.
Lawwell said: "The signing of Odsonne from Paris Saint-Germain demonstrates our absolute commitment to ensuring we give our fans a club they can be proud of."