Conor McCann's double helped Antrim to a nine-point success in Saturday's All-Ireland SHC qualifier at Casement Park.
The forward netted after nine minutes only for Westmeath to hit back through Paul Greville's goal two minutes later.
McCann struck again on 30 minutes to leave the Ulster side leading 2-12 to 1-7 at the break.
Westmeath fought back to reduce the gap to three but the hosts pulled clear again and they will now take on Carlow in Belfast next Saturday.
Neil McManus fired over 11 points for the Saffrons while Westmeath's Brendan Murtagh was just a point behind.
The game against Carlow will be part of a Casement Park double-header next Saturday with the Antrim footballers facing Westmeath in an All-Ireland first round qualifier.
Antrim: C O'Connell, C McGuinness, C Donnelly, Kieran McGourty, A Graffin, M Herron, N McAuley, P Shiels, C Herron, S McCrory, K Stewart, N McManus, C McCann, D Hamill, J Black. Subs: C Cunningham, Barry McFall, T McCann, K McKeague, C McFall, K Molloy, E McCloskey, K McKeegan, M Donnelly, P Doherty, J McCouaig, J Scullion, C Carson.
Westmeath: C Scally, C Flanagan, D McCormack, A McGrath, E Price, A Mitchell, P Gilsenan, P Dowdall, B Smyth (capt), C Curley, P Greville, B Murtagh, J Shaw, D McNicholas, D Carthy. Subs: S McGovern, J Gilligan, A Devine, A Craig, A Price, C Boyle, A Dermody, E Og Clarke, C Mackey, B Connaughton, K Martin.