The 20-year-old midfielder is regarded as one of the biggest talents around in his age category and had also been linked with clubs such as Manchester United, Inter and Atletico Madrid in recent months, but Monaco have won the race for his signature.
Anderlecht general director Herman Van Holsbeeck already announced earlier this week that the Belgium international was on his way to the Ligue 1 champions and he has now signed a contract with Monaco until June 2022.
— CHAMPIONS (@AS_Monaco) May 24, 2017
"I am thrilled to be a part of this team next year," Tielemans commented on his transfer.
"Monaco are a club with an ambitious project and have a reputation for developing youngsters.
"I have spoken a lot with Yannick Carrasco about Monaco while we were with the national team.
"I am very happy to be here. I am going to do everything within my powers to pay back Monaco for the faith shown in me."
Tielemans came through the ranks of the Anderlecht youth academy and made his first-team debut at the tender age of 16.
He had since developed into a key figure at the Brussels giants, making over 150 appearances in all competitions for the club.
The Belgium international scored 13 goals in 37 league appearances this term to help Anderlecht to the Belgian title.