Dundee United's first season in the Championship was under the management of Ray McKinnon. United won the Challenge Cup by beating St Mirren 2–1 in the final and they reached the play-off final for the Premiership. However they lost narrowly 1–0 to Hamilton.
The second season in the second tier was less successful, as manager McKinnon was sacked and replaced with Csaba László; after a very disappointing season, United lost in the play-off semi-final to eventual promotion winners Livingston.
After a poor start to the 2018–19 season the manager was once again sacked and replaced with Robbie Neilson. The team finished second in the Championship but lost in the play-offs to St Mirren, missing four penalty kicks in the process.
United started the 2019–20 season in title-winning form, maintaining the top spot since the opening weekend, but the season was postponed due to the global COVID-19 pandemic on 13 March 2020. On 15 April 2020, the SPFL plan proposing an end to the season was approved. A 14-point lead over second place Inverness CT saw United crowned champions and subsequently promoted back to the Premiership.
On 21 June 2020, the club announced that they were parting ways with manager Robbie Neilson, who agreed a deal to return to newly relegated side Heart of Midlothian.