The only other amateur to make the cut was Yunseo Yang, who finished T54 at nine-over par. The South Korean earned her place at Royal Lytham after winning the Women's Amateur Asia-Pacific at Royal Wellington in February.
Paula becomes the fifth player to claim the title on two occasions and the first since Jeeno Thitikul in 2018 and 2019.
It was another impressive display at the AIG Women's Open for the Stanford University student, who was making just her second appearance at the championship.
"I think there are a lot of learnings," she added when reflecting on her week on the major stage. "Just seeing myself up there ahead of the weekend was a challenge and I haven't been in that position before... [I will be] taking some good lessons with me and hopefully work them out for the future."
The Smyth Salver has been contested since 1979, with England’s Sue Hedges becoming the very first recipient.
Several major stars have added their names to the roll of honour over the years, including Michelle Wie, Mel Reid, Leona Maguire, Rose Zhang, and Lottie Woad.
Most notably, four former Smyth Salver winners have gone on to taste victory in the championship itself: Marta Figueras-Dotti, Anna Nordqvist, Georgia Hall, and 2024 champion Lydia Ko.