The card will mark the UFC's debut on ESPN+.
Lineker (31-8) was slated to fight former UFC bantamweight champion Dominick Cruz in January, but the fight was canceled after Cruz withdrew because of an injury.
Lineker is coming off a third-round knockout of Brian Kelleher in May.
Sandhagen (9-1) is 2-0 in the UFC. He most recently defeated Iuri Alcantara via second-round TKO in August.