Rowsell claimed London 2012 gold alongside Dani King and Laura Trott in the team pursuit but swapped the track for the road and demonstrated her talents for both as she claimed victory.
The 24-year-old posted a time of 49 minutes 25 seconds for the win, with Olympic road race silver medallist Lizzie Armistead having to settle for runner-up 32 seconds behind.
Rowsell posted a time that was 16 seconds faster than Armistead on the opening lap and nearly doubled that gap by the finish – insisting it was a great way to kickstart her season.
"I was quoted in the media that I was focussing on the road this year, but actually I just wanted a break over the winter, just a normal winter rather than trying to peak for the track worlds in February," she said.
"But to be honest I felt a bit lost at the start of the season, I didn't know if I'd be out of the back or what.
"So I set this as a target quite early in the season just because it was something I knew I could come and do. Initially I was quite worried about the distance being 22 miles, but now I think they suit me actually.
"It was tough being 22 miles. I've done three 25s this year and I've learned I can go hard from the start, but not really, really hard, you can't pace it too much but this course was a bit hilly.
"From the start you're up a hill and I think a few of the boys found that and were suffering for the whole race.
"I tried to pace it to begin with but I felt pretty bad to begin with, on the first lap, but felt better on the second lap, which is a good way round I suppose."