The world number 25 defeated Liz Young with a birdie on the first extra hole in Hampshire.
Both players carded level par rounds of 70 in overcast and windy conditions.
Young, who organised the event at her home club, played in the first group out and set the clubhouse target, but she waited for three and a half hours before Hull matched her score.
Hull was two strokes clear with two holes to play but double bogeyed the par-four 17th hole, after hitting a rescue wood off-line right into a ditch from the tee.
She had a chance to birdie the 18th to win in regulation play but missed the putt.
The Solheim Cup player then took her chance at the first extra hole, rolling in a similar putt from 12 feet beyond the hole, before being presented with a rose bowl and winner’s cheque for £5,000 by Kate Rose, wife of PGA Tour star Justin, who together sponsored the series.
It was Hull’s first competitive round for almost five months and she said: “I’m just so happy to be playing professional golf again and have a scorecard in my hand.
“I’ve missed it loads. I love playing golf. I’m pretty much golfed out because I’ve been playing every day, but I can’t wait to get back out on tour.
“I want to thank Justin and Kate Rose for putting these events on. You need to be playing to get back in the mindset.
“I’ve been playing a lot for the last few weeks and I played eight days on the trot, but it’s not the same as having a scorecard in your hand.
“I’ll go back to America in four weeks’ time, so hopefully this will get my brain back into tournament golf.”
There will be a Rose Ladies Series event played on Thursday each week, leading up to the Grand Final on August 6 and 7.