Boutier, a member of the last two triumphant European Solheim Cup teams, birdied the last from 20 feet to pip Henry by a shot in the 54-hole title battle.
“I’m really happy with how I played,” said the Scot, who had just one bogey in her last 36 holes.
“I feel like I hit a lot of good shots on the back nine, but I just didn’t manage to make any birdies.
Second place isn’t what you dream of, but I’m still really happy because it is a good result and I’m happy to be back in contention.”
Henry, a two-time LET winner, picked up a cheque for around £23,000 for her best performance on the circuit in recent seasons.
“I didn’t make any bogeys so I’m really happy with that because it shows that it was really solid golf,” she added.
“I gave it my best but that putt on the last from Celine was outstanding - and that’s why she’s a Solheim Cup player, she was brilliant.”
Boutier, who made her pro debut in the same event in 2016 before ending up second to Nelly Korda three years later, finished with an 11-under-par 202 total as she recorded her third LET triumph.
“I couldn’t have hoped for a better ending,” Boutier said. “It was a special week all round."