On 31 August 2017, Sporting agreed a £22 million fee for Silva to move to Leicester City, pending international clearance.
The documents relating to his transfer did not reach FIFA until 14 seconds after the deadline; thus, he remained ineligible to play for the club until the next transfer window.
In a statement on 24 October, Leicester chose not to appeal to the Court of Arbitration for Sport as it was made clear to them that "FIFA will not support an expedited process"; in an interview with The Guardian in March 2018, he said it was "a very poor decision" by FIFA, despite his appeals, to uphold his ban.

Silva was officially registered on 1 January 2018, and made his debut that same day as a late substitute in a 3–0 win at home to Huddersfield Town in the Premier League.
He was given the number 14 jersey, referring to his transfer difficulties.
In a 2–0 defeat of Watford on 20 January, he came on for Jamie Vardy in the 89th minute and provided the assist for Riyad Mahrez's goal in stoppage time.

Silva struggled for game time under manager Claude Puel, having not started a league match since 10 August 2018.
He made only five appearances in all competitions, and was not included in the squad for a league match after 22 September.

On 31 January 2019, Silva joined AS Monaco FC – coached by his compatriot Leonardo Jardim – on loan until June, with Youri Tielemans moving in the opposite direction.
He made his Ligue 1 debut on 2 February, playing 18 minutes in the 2–1 home victory over Toulouse FC after replacing fellow Portuguese Gelson Martins.

Despite a change of Leicester manager prior to 2019–20, Silva was still told that he was free to leave the club.
On 23 August 2019, he rejoined Monaco on another loan.
He contributed two assists in 22 appearances, before the season was abruptly concluded due to the COVID-19 pandemic.
On 31 August 2017, Sporting agreed a £22 million fee for Silva to move to Leicester City, pending international clearance. The documents relating to his transfer did not reach FIFA until 14 seconds after the deadline; thus, he remained ineligible to play for the club until the next transfer window. In a statement on 24 October, Leicester chose not to appeal to the Court of Arbitration for Sport as it was made clear to them that "FIFA will not support an expedited process"; in an interview with The Guardian in March 2018, he said it was "a very poor decision" by FIFA, despite his appeals, to uphold his ban.
Silva was officially registered on 1 January 2018, and made his debut that same day as a late substitute in a 3–0 win at home to Huddersfield Town in the Premier League. He was given the number 14 jersey, referring to his transfer difficulties. In a 2–0 defeat of Watford on 20 January, he came on for Jamie Vardy in the 89th minute and provided the assist for Riyad Mahrez's goal in stoppage time.
Silva struggled for game time under manager Claude Puel, having not started a league match since 10 August 2018. He made only five appearances in all competitions, and was not included in the squad for a league match after 22 September. 
On 31 January 2019, Silva joined AS Monaco FC – coached by his compatriot Leonardo Jardim – on loan until June, with Youri Tielemans moving in the opposite direction. He made his Ligue 1 debut on 2 February, playing 18 minutes in the 2–1 home victory over Toulouse FC after replacing fellow Portuguese Gelson Martins.
Despite a change of Leicester manager prior to 2019–20, Silva was still told that he was free to leave the club. On 23 August 2019, he rejoined Monaco on another loan. He contributed two assists in 22 appearances, before the season was abruptly concluded due to the COVID-19 pandemic.
Adrien Silva