Khalidov, who was 1-1 against the UFC veteran, earned a 2020 victory with a flying switch-kick knockout. He landed the exact same strike to get the job done 63 seconds into the third round of their rubber match.
The 42-year-old spent the second round exchanging leg attacks with Askham on the ground, but no one managed to secure a proper hold to force the tap. As the third stanza began and both middleweights landed unintentional low blows to force brief halts on the contest, Khalidov landed the flying kick as soon as the action restarted, following up with punches to put him out cold.
Watch the finishing sequence below.
A former KSW middleweight and light heavyweight champion, Khalidov (37-8-2) is now 3-1 since losing a decision to Askham in 2019, a run that includes two knockouts over the English fighter and a first-round stoppage against Mariusz Pudzianowski at heavyweight.
Askham (19-6) was riding a four-fight winning streak since parting ways with the UFC in 2017 when he started the Khalidov trilogy in 2019.