Having made one EFL Cup appearance for Birmingham in 2019–20, Lakin joined EFL League Two club Stevenage on 22 August 2019 on loan for the rest of the season. He went straight into the starting eleven for the league visit to Mansfield Town two days later, and played the whole 90 minutes as the match ended goalless. A thigh injury suffered during his debut kept him out for two months: he returned to action on 26 October in a 1–0 win at home to fellow strugglers Morecambe. He scored his first senior goal on 18 January 2020 to round off a 4–0 win away to Cambridge United. He had made 25 appearances in all competitions by the time the League Two season was first suspended and then ended early because of the COVID-19 pandemic.