The world number closed out the victory despite a few service wobbles late on, improving her win-loss record against Rybakina to 8-5.
Iga Swiatek, who beat American 13th seed Amanda Anisimova 6-0, 6-0 in the Wimbledon final on Saturday to win her sixth Grand Slam title.
Poland's Agnieszka Radwanska moved within one win of securing a place at the WTA Finals after thrashing Czech Karolina Pliskova 6-3, 6-1 in the semi-finals of the Tianjin Open on Saturday.
Paula Badosa overcame a slow start to take down Belarusian top seed Aryna Sabalenka after Maria Sakkari continued her dominance of Iga Swiatek in the round-robin stage of the WTA Finals in Guadalajara, Mexico on Thursday.
ATP, WTA cancel China events, including Shenzen Finals
Czech Lucie Safarova took the final qualifying spot for the end-of-season WTA Finals after Spain's Carla Suarez Navarro was knocked out of the Kremlin Cup quarter-finals on Thursday.
Anett Kontaveit handed Czech Karolina Pliskova a 6-4, 6-0 drubbing to become the first player to qualify for the semi-finals while Garbine Muguruza came from behind to defeat Barbora Krejcikova 2-6, 6-3, 6-4 at the WTA Finals in Guadalajara, Mexico on Friday.
The Finals, contested by the world's top eight singles players and eight doubles teams, was moved out of China's Shenzhen after last year's event was cancelled due to the COVID-19 pandemic.
World number one Novak Djokovic saw off Canadian Denis Shapovalov 6-3, 6-4 to win his fifth Paris Masters title on Sunday in a warning to his rivals ahead of the ATP Finals, while Ashleigh Barty finished the season in style by beating defending champion Elina Svitolina 6-4, 6-3 to add the WTA Finals title to her end-of-year world number one rank.ing
Spain's Paula Badosa ground out a 7-6(4), 6-4 victory over Maria Sakkari at the WTA Finals in Guadalajara, Mexico on Saturday and advanced to the semi-finals with two wins from two matches in Group Chichen Itza after Aryna Sabalenka beat Iga Swiatek.
Top seeds Sania Mirza and Martina Hingis continued their rampaging form and recorded a straight set victory in their opening match of the year-ending $7 million WTA Finals in Singapore.
Zhang Shuai stunned Wimbledon Champion Angelique Kerber 6-1, 2-6, 6-0 in the China Open on Thursday to set up a quarter-final clash with Naomi Osaka.
Maria Sharapova continued her mastery of Romania's Simona Halep with a high quality 6-4, 6-4 victory filled with bruising baseline rallies to edge closer to a last four berth at the WTA Finals on Tuesday.
Indian tennis ace Sania Mirza and her Swiss partner Martina Hingis ended their dream run of 2015 on a high, winning their ninth women's doubles title, in Singapore, on Sunday.
Factbox on American second seed Coco Gauff, who defeated Belarusian world number one Aryna Sabalenka
President Pranab Mukherjee on Tuesday congratulated tennis ace Sania Mirza for winning the season-ending WTA Finals women's doubles title.
World number one Simona Halep pulled out of next week's WTA Finals due to a lower back injury.
Serbia's Ana Ivanovic just missed out on a place in the semi-finals of the season-ending WTA Finals despite beating Simona Halep in the final group match on Friday.
Poland's Agnieszka Radwanska booked a spot at the end of season WTA Finals in Singapore after outclassing Montenegrin Danka Kovinic to win the Tianjin Open in China on Sunday.
American teenage sensation Coco Gauff progressed to her maiden WTA final as she eased past Germany's Andrea Petkovic 6-4, 6-4 at the Linz Open on Saturday. The 15-year-old Gauff became the youngest player to reach a WTA final since Czech Republic's Nicole Vaidisova won the Tashkent Open in 2004, also aged 15.
A day after suffering her heaviest defeat since she was a teenager, Serena Williams was back to her brilliant best as she swatted aside Eugenie Bouchard 6-1, 6-1 in her final round robin match at the WTA Finals on Thursday.
The 16-times Grand Slam champion, who has been slightly ill lately, was kept on his toes before racing to victory to set up a meeting with seventh seed Stefanos Tsitsipas.
Marin Cilic and Milos Raonic booked their spots in the Paris Masters second round on Monday, while Roger Federer pulled out of the tournament with next month's ATP Finals on the horizon.
Three women in the field have topped the world rankings this season, incumbent Simona Halep and her predecessors Garbine Muguruza and Karolina Pliskova, but none of them have been able to kick on and cement their place as the tour's dominant player.
An emotional Agnieszka Radwanska claimed her maiden WTA Finals title with a roller-coaster 6-2, 4-6, 6-3 victory over Czech Petra Kvitova in an absorbing encounter at a packed Singapore Indoor Stadium on Sunday.
Angelique Kerber was forced to dig deep in her WTA Finals opener before the German world number one battled past Dominika Cibulkova 7-6(5), 2-6, 6-3 in a high-class baseline slugfest at the Singapore Indoor Stadium on Sunday.
World's numero uno women's doubles pair of Sania Mirza and Martina Hingis continued their rampaging form and extended their monster winning streak to 20 matches in a row after reaching the semi-finals of the WTA Finals in Singapore.
Dominika Cibulkova completed a remarkable debut at the WTA Finals when the Slovakian world number eight stormed to victory with an unlikely 6-3 6-4 triumph over top seed and world number one Angelique Kerber in the title showdown on Sunday. Cibulkova lost her first two round robin matches before beating Simona Halep to squeeze into the semi-finals and her victory on Sunday matches the feat of 2015 winner Agnieszka Radwanska, who captured the title with a 1-2 pool record.
World No 1 Serena Williams was handed the best possible draw for her WTA Finals title defence with the 33-year-old American grouped with two injury doubts and avoiding the in-form players.
Czech Barbora Krejcikova on Sunday called for respect and professionalism in sports media as she hit out at "unprofessional" remarks made about her appearance during a broadcast on the Tennis Channel.
Svitolina arrived in Singapore out of form yet determined to "silence the haters", who she said believed she did not deserve to be in the tournament, and the Ukrainian has played brilliantly to win all three pool matches and her semi-final.
Garbine Muguruza continued her dream debut at the WTA Finals by completing round robin play with a perfect 3-0 record to advance to the semi-finals after a hard fought 6-4, 4-6, 7-5 victory over Petra Kvitova on Friday.
Garbine Muguruza made an imposing start to the WTA Finals by confidently swotting aside Czech Lucie Safarova 6-3, 7-6 (4) in their White Group opener on Monday.
Caroline Wozniacki claimed the biggest title of her career after the Dane staved off a ferocious Venus Williams fightback to take a 6-4, 6-4 triumph in the WTA Finals title showdown at a captivated Singapore Indoor Stadium on Sunday.
Venus Williams gained revenge for her Wimbledon final defeat by Garbine Muguruza when the American advanced to the last four of the WTA Finals with a gutsy 7-5 6-4 victory over the Spanish world number two on Thursday.
Osaka, who returned to the tour a year ago after a long maternity break, had shown glimpses of the form that won her four major titles on her run to the final in Auckland.
World number two Simona Halep beat Maria Sharapova 6-2, 6-2 in the China Open third round on Wednesday for her first win over the Russian in eight attempts.
Angelique Kerber showed more passion in the media centre than on the court when she crashed out of last year's WTA Finals, the German angered by the format and frustrated by her inability to win the set off an eliminated opponent she needed to advance.
Serena Williams shook off the rust and a feisty challenge from Serbia's Ana Ivanovic to open the defence of her WTA Finals title with a 6-4, 6-4 victory in the opening match of the elite eight-player tournament on Monday.
Caroline Woznaicki produced an almost perfect display to dismantle world number one Simona Halep 6-0 6-2 at the WTA Finals on Wednesday, the Dane recording her second dominant victory in as many matches.
