Coming on the penultimate day of the campaign, the result will have no impact on where the Lily Hill men finish in National Three South East, but it does at least mean they gain revenge for their single-point loss to the same opponents earlier in the season.
Bracknell took the lead when Chris Brember burst through Gravesend's defensive line to score an unconverted try.
A Dave Dorton penalty was all the hosts had to show for their efforts at the end of the first quarter, and they fell further behind when Nico Maybury touched down.
But with Nowak unable to add the extras, Gravesend drew level thanks to a try from Tom Goss that Dorton converted.
The hosts then took the lead for the first time in the match when Ziggy Stevens forced his way through the defence and touched down.
Dorton was forced to attempt a drop goal for the conversion as the ball twice fell from tee, and he was unsuccessful with his effort.
The score looked to have given the hosts the impetus heading into the interval but, in the fifth minute of added time, Maybury swung the game back in Bracknell's favour with his second try of the match.
Nowak converted to give the Lily Hill men a deserved 17-15 lead at the interval.
Gravesend, though, upped their game after the break and they earned a series of penalties close to Bracknell's line.
One of them earned Steve Bryant a yellow card for handling at the ruck, giving the hosts the chance to touch down through Sox Stevens.
Dorton then added a penalty to make it 23-17 and with time running out it looked as though Bracknell's fate was sealed.
But a poor clearance kick gave the visitors the ball and Bember crossed in the corner following a quickly taken penalty to narrow the difference to 23-22.
Nowak then kicked a brilliant conversion with the final moment of the match to seal a single-point win for Bracknell.
Alan Leishman's side finish their season with a home game against Dorking on Saturday (3pm ko).