Mladenovic, who won six Grand Slam doubles titles between 2018 and 2022, suffered a long-term injury that left her on crutches last year. She paired up with Guo earlier this year.
"It feels like a dream... I definitely cannot believe what just happened now," Mladenovic, 34, said after her maiden Wimbledon win.
10th seeds Guo and Mladenovic were quick to read Dabrowski's early lobs and raced to a 5-0 lead. The Canadian-Brazilian pairing of Dabrowski and Stefani fought back to win the next three games, but it was not enough to save the set.
The second seeds looked much more in their element as they pushed for a break in the second set, but their opponents saved two break points as Mladenovic's strong forehands across the court helped them stay even at 5-5.
Guo's backhand returns from the net set up a break point in the 11th game, which the Chinese 28-year-old, playing in her first major final, won with a cross-court backhand at a tight angle.
Serving for the championship, a clinical Mladenovic secured victory with a forehand that her opponents could only lash back into the net.
"I just feel so lucky to have you on my side and with this trophy now. Thank you for choosing me... trusting me," an emotional Guo told Mladenovic.
Mladenovic said she was thankful to have Guo as her partner.
"I had no ranking, I had a tough injury last year, and (Guo) did not hesitate at all. I am very proud to be standing here with her," she added.
Wimbledon 2026
Wimbledon is taking place from June 29th to July 12th at the All England Club in south-west London. With 128 players in the draw, it is the third of the four Grand Slams of the tennis season and the only one played on grass.
Men's singles draw and results | Women's singles draw and results | All you need to know about the tournament | Find all our Wimbledon coverage here