Swiatek and Hurkacz eased past Sorribes Tormo and Alejandro Davidovich Fokina (24) 6-0, 6-0 in the mixed doubles decider to ensure the top seeds finished as Group A winners in the 18-nation event that offers $10 million in prize money.
"I'm happy right now to have another chef in the bakery," said world number one Swiatek, whose ability to crush singles opponents by winning sets without conceding games has sparked "Iga's Bakery" memes on social media.
"No, I'm kidding. On Twitter they said the bakery should be closed on New Year's Eve, but here we are. I'm happy I played so well and Hubi's a great partner for mixed doubles."
Swiatek, who beat Brazil's Beatriz Haddad Maia on Saturday, earlier dragged Poland back into the tie against Spain with her win over Sorribes Tormo after Davidovich Fokina gave his team the lead with a 3-6, 6-3, 6-4 victory over Hurkacz.
Casper Ruud also stepped up his preparations for the January 14th-28th Australian Open with a pair of wins as he guided Norway to a 2-1 victory over Croatia in Sydney.
The former world number two beat Borna Coric 6-4 6-1 to draw his nation level after Donna Vekic defeated Malene Helgo 7-5, 3-6, 6-3. He then partnered Ulrikke Eikeri to defeat Vekic and Ivan Dodig 6-2, 3-6, 10-7.
Australia joined Poland in the last eight as Matthew Ebden and Storm Hunter saw off Americans Jessica Pegula and Rajeev Ram 6-3, 6-1 to seal top spot in Group C.
Alex de Minaur put the hosts on course for victory pulling off a 6-4, 6-2 win over Taylor Fritz, before Pegula got defending champions the United States back on track defeating Ajla Tomljanovic 7-6, 6-3.
France prevailed 2-1 over Germany as Caroline Garcia and Edouard Roger-Vasselin saved match points to outlast Angelique Kerber and Alexander Zverev 7-6, 2-6, 12-10.
They could win Group D if they beat Italy on Wednesday.
"We managed to stay solid and to keep really focussed," said Garcia, who dug deep to beat Kerber 1-6, 6-2, 6-2 in her season opener after Alexander Zverev downed Adrian Mannarino 4-6, 6-4, 6-3 to put Germany ahead.
