Ukraine's Svitolina beat Paolini in the women's draw just hours after Monfils stunned Taylor Fritz on the same Margaret Court Arena in the men's singles.
The 38-year-old Frenchman Monfils was watching from Svitolina's on-court coaching box as the couple both reached the last 16 of the first Grand Slam of the year.
"It was a crazy battle today. I got inspired after my husband's win," said Svitolina, the 28th seed.
"I watched a little bit of that match, of course it was tough to miss."
Svitolina stepped up the pace in the second set after dropping five games in a row to lose the first against the Italian Paolini. She moved in closer to take the ball earlier and moved the speedy Paolini around with huge forehands.
Svitolina took a tight second set after an early break then completely ran away with the third as Paolini had no answers to her shot-making.
"To be fair I played so bad in the first set I had to really push through," said Svitolina.
"I'm really happy with the way I came back into the match. Really happy with the performance in the end."
Svitolina sets up a clash against unseeded Russian Veronika Kudermetova, who earlier beat Brazil's Beatriz Haddad Maia 6-4, 6-2.
In 2024, Paolini became the first Italian woman to make the last 16 at all four Grand Slams in the Open Era and won the title in Dubai in a breakthrough season that propelled her into the top five. She also reached maiden major finals at Roland Garros and Wimbledon but saw her run come to a juddering halt in 1hr 46min in Melbourne.