ParalympicsGB had a near-perfect morning with three golds and a silver from four races at the Vaires-sur-Marne stadium.
Rowles, 26, looked elated after claiming her historic third Paralympic gold in the PR2 mixed double sculls with Stevenson after a thrilling final.
It was a stunning victory. The Britons had been more than a boat length behind China’s Liu Shang and Jiang Jijian but moved up the gears in the last 300m to beat them on the line.
Rowles also won the race at Rio 2016 and Tokyo 2020 with former partner Laurence Whiteley.
Assessing their narrow victory, Rowles said: “It’s the Paralympic Games; you either show up or you show out and I said that in the first race that it was going to come down to the line.
“The level of competition is high and I said to Gregg, ‘when I say go, you go’, and he did that today and we just went for it. [We] stayed in our lane, did our own thing and came through as champions.”
Pritchard earned gold in the PR1 single sculls ahead of Italy’s Giacomo Perini, after setting a Paralympic record in qualifying.
Great Britain’s PR3 mixed coxed four crew continued the golden run. Frankie Allen, Giedre Rakauskaite, Josh O’Brien and Ed Fuller, coxed by Erin Kennedy, retained the title they won in Tokyo.
To finish off the morning, GB’s Annabel Caddick and Samuel Murray secured silver in the PR3 mixed double sculls after holding off the threat of Germany’s Jan Helmich and Hermine Krumbein. Australia’s Nikki Ayers and Jed Altschwager claimed the gold.