French champions Monaco have won the race for Tielemans's signature, however, handing him a five-year contract to add another highly promising youngster to their talented squad.
"I am thrilled to be a part of this team next year," he told the club's official website. "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 scored 29 goals in 171 appearances in all competitions for Anderlecht, including 13 in 37 league games last term to help his side to the Belgian title.