Rugbypass reports Lancaster will join Warriors when his contract with Racing 92 runs out at the end of next month. Rugbypass first linked Lancaster with a move to Scotstoun back in April but Warriors appeared to pour cold water on any deal.
The ex-Leicester Tigers, Nottingham, Yorkshire Carnegie and Ealing Trailfinders player, is Scotland-qualified via his Dumfries-born grandmother.
Lancaster's father is former England, Leinster and Racing 92 coach, Stuart, who represented Scotland at age group level.