The hosts led 3-0 at the break thanks to goals from Jill Scott, Isobel Christiansen and Lucy Bronze.
Nikita Parris added a fourth, Christiansen netted her second from the spot and Georgia Stanway made it six.
Caroline Weir netted a consolation goal as Bristol were condemned to WSL 2.
The result ensured that Birmingham City retain their top-flight status, while City go top of the table ahead of Chelsea's evening fixture at Liverpool Ladies.
Manchester City defender Jennifer Beattie told BBC Sport:
"It feels good to get another three points as the main thing for us was just to focus on the win.
"There's always more to come from us, that's why we work so hard on the training ground.
"It's just stepping stones, if we get Champions League that'll be fantastic but if we get anything more then we'll be ecstatic."
Bristol Academy manager Willie Kirk told BBC Sport:
"It's relegation and the harsh realities of it is kicking in so it's a very quiet and subdued dressing room.
"Personal and professional pride has to kick in and that's what we've got to do next week.
"We need to have that pride and ambition to finish the season on some sort of positive."
Manchester City: Bardsley, Bronze (McManus 82), Houghton, Beattie, Stokes, Walsh, Scott, Harding (Corboz 61), Christiansen, Johnson; Parris (Stanway 57).
Substitutes not used: Radtke, Lipman Brougham, McIver.
Bristol Academy: Earps, Dykes, Brown, Ladd (Short 70), Brummel (Pinto 76), Ingle, Evans, James, Murray, Weir, Jade.
Substitutes not used: Reid, Lawrence, Popadinova, Passariello.
Manchester City ensured the Women's Super League One title race will go to the final day of the season after consigning Bristol Academy to relegation with a 6-1 win.