England fast bowler Bell claimed four for 10 to move to nine wickets in the tournament, two behind team-mate Amanda-Jade Wellington, who took three for 18.
Rockets' 88 for eight was never competitive and was proved so as Smriti Mandhana and Danni Wyatt smashed 57 off 31 balls and 36 off 25 respectively to knock off the modest total in 56 balls to win by 10 wickets.
Brave maintain their perfect record and will head straight to the final if they beat Northern Superchargers or if Oval Invincibles and Birmingham Phoenix slip up in their final two fixtures. Rockets need one of Invincibles and Phoenix to lose both their remaining games to progress.
Rockets were put in and other than an exciting cameo from Marie Kelly massively struggled with conditions, whether it was the swing of Bell or the spin of Wellington.
Bryony Smith became the first woman to be dismissed in the first five-ball set of an innings in this year's edition when she swung a short Bell delivery to Danni Wyatt at deep midwicket.
The only time Rockets looked on top was when Kelly thumped Anya Shrubsole through the covers and then for a six, tipped over the boundary by a full-stretch Wyatt.
Kelly slowed and tried to chip over the in-field, only to give Bell her second wicket by finding cover, and Elyse Villani looked set on 25 before slicing Wellington to extra cover.
Rockets only scored a single boundary in the second half of their innings, a six from Mignon du Preez, as Brave turned the screw in time with the drizzle dissipating.
The need to catch up on runs saw five wickets fall in the last 21 balls, with only nine runs coming. They only managed eight boundaries in total to underline their lowest boundary percentage in the tournament.
Nat Sciver was put out her misery after a hellish 19 from 30 balls when she was stumped off Wellington, who also found rival Australian leg-spinner Alana King gloving to slip while attempting to reverse before Du Preez was caught slog-sweeping Georgia Adams.
Bell finished things up with an exemplary final five balls, with Katherine Brunt and Sarah Glenn both caught at point to the final two deliveries of the 100.
Mandhana slapped the first ball of the chase to the point boundary and did not look back. A hat-trick of fours in a row off Sciver made things even easier.
Her opening partner Wyatt got slightly lucky an edge went between keeper and slip off King but that only emboldened her and five boundaries in seven balls later and she had overtaken the Indian.
But Mandhana re-took her advantage, slogged King back over her head, and celebrated a 30-ball fifty before winning the game with another maximum.
The pair blitzed 16 fours and two sixes to give a set of unflattering bowling figures.
The win with 44 balls remaining was the most unused balls in a chase across both years of the women's Hundred.