On 10 October 2018, Smith was appointed manager of 14th-placed Championship club Aston Villa, with John Terry as his assistant coach. He was named as the EFL's manager of the week after overseeing a 3–0 win at Derby County on 10 November. He immediately managed to reinvigorate the "Villans" attack, and only a controversial injury-time equaliser from local rivals West Bromwich Albion at The Hawthorns denied them a place in the play-offs by 7 December. However Villa's form dipped dramatically in the three months after Jack Grealish was sidelined with a shin injury picked up in that match, but on 2 March, Smith gave Grealish the captaincy on his return to the first-team and the 23-year old inspired an important 4–0 victory over play-off rivals Derby County. Smith was given that month's EFL Championship Manager of the Month award after achieving five wins in five games, including a victory over Second City derby rivals Birmingham City. On 22 April 2019, Smith lead Aston Villa to break an 109 year old club record for longest winning run after defeating Millwall 1–0 at Villa Park to make it 10 successive victories in 10 matches. The record had previously been held at nine straight wins. On 11 May, Smith oversaw his 18th win with Aston Villa as they came from behind to beat West Brom 2–1 in the first leg of the Championship play-off semi-finals. Three days later, Villa came from behind at West Brom to win on penalties and secure a place in the play-off final. Villa went on to win promotion to the Premier League with a 2–1 victory over Derby County.