The victorious duo held their nerve to prevail 7-6 (7-3) 7-6 (7-3) after Stefani appeared to be hampered by a leg issue in the second set on Thursday evening.
As Siniakova sealed victory with an overhead smash, the duo celebrated their first title together, Siniakova's maiden mixed doubles Grand Slam and Verbeek's first Grand Slam triumph of any kind.
"It's very special, I mean it means a lot -- we had a lot of fun on the court and I really enjoyed it, it was a really amazing time here," Siniakova said after lifting the trophy.
For the 29-year-old Siniakova, the win added to her 10 Grand Slam women's doubles titles, including the Australian Open crown that she annexed with American Taylor Townsend in January.
"Katerina, thank you so much, it's been an honour to compete next to such a great doubles legend, one of the best to ever do it and thank you for making this a Thursday I will remember for the rest of my life," the 31-year-old Verbeek said.
Salisbury, who faced the disappointment of home fans hoping to see a British champion, said margins did not fall in his and Stefani's favour.
"It's always tough to lose a final but they played amazing, so congratulations. They were too good in the tiebreaks today," Salisbury said.
