On 15 June 2016, Lewis signed for Scottish Premiership club Aberdeen.  He made his debut for the club on 30 June 2016, in a Europa League First qualifying round tie against Fola Esch.  Lewis started all matches for the Dons in 2016–17, and signed a new deal at the end of the season to keep him at the club until 2020.  Lewis continued to play regularly for Aberdeen over the next two seasons, and extended his contract with the club until 2024 in May 2019.