Last year, the Kiwi won the WTA 1000 tournament with Asia Muhammad; this year she repeated that feat with regular partner Gaby Dabrowski.
It is the first time Routliffe and Dabrowski have won a WTA 1000 title together and is their second title this year.
Routliffe and Dabrowski defeated Guo Hanyu from China and Russia's Alexandra Panova 6-4 6-3, in a finals match that lasted one hour and 20 minutes.
The Kiwi/Canadian team got the only break of serve in the opening set of the final and, in the second set, broke their opponents three times.
It was Routliffe and Dabrowski back to their best. The Canadian, who was dealing with breast cancer this time last year, gave an emotional speech at the trophy presentation.
"Exactly one year ago, I was going through radiation treatment at the Mayo Clinic in Jacksonville.
"Erin's best friend, Asia Muhammed, stepped in and played this tournament and they took the title, which was really fun to watch them do from afar.
"But I feel very fortunate to be able to compete this week and fill some very big shoes, Asia's shoes. So it's been super special to compete here alongside Erin."
Routliffe paid tribute to all of those who had supported her and Dabrowski.
"Our team, of course, everyone here and everyone watching back at home or wherever they are in the world, we have so many people behind us. It really does take a village to make us who we are and to give us the success that we have."
The New Zealander then spoke to her long-time doubles partner.
"Gaby, we have had a rough year and we've stuck together. I think this title means a lot to both of us."
The pair next head to Monterrey in Mexico for one more tournament before the US Open begins on August 24.
Meanwhile, singles player Lulu Sun has also been in action in Monterrey, advancing from qualifying into the main draw.
The Kiwi defeated France's Diane Parry 6-4 7-6(5) in the final round of qualifying on Monday morning, setting up a rematch with Czech player Linda Noskova.
The two met in last year's Monterrey final, which was Sun's first appearance in a WTA final, with Noskova winning 7-6(6) 6-4.
