Silva is expected to join the Foxes in a £21m deal and may join current team-mate Islam Slimani in a £50m double-switch.
The 27-year-old - who has been at the club his whole career - thinks that now is the time to leave and confirmed his move to the King Power Stadium in an interview with Portuguese newspaper 'O Jogo'.
"Yes, I confirm this proposal. Leicester is very interesting and corresponds to my career goals," he said.
"After the past 15 years at Sporting, this opportunity is something exceptional for me and can allow me to express and impose myself in another championship, and also to evolve in the Premier League, which is a stunning league.
"I love Sporting as a family and I dedicated myself to the club since I was 12 years old.
"With Sporting I lived many moments of happiness. I can say that I grew up with the club. At 27 years old, and after so many years of loyalty, I think that no one will criticise me for wanting to embrace this challenge".
Adrien Silva has played 199 games for Sporting Lisbon, scoring 33 goals and was part of Portugal's Euro 2016-winning squad.