While ex-fiancee Rory McIlroy has stolen the headlines with his results on the golf course since breaking up with her, Wozniacki has lifted her game similarly - resembling the form that took her to the top ranking in October 2010.
The 12th seed in Cincinnati, Wozniacki beat left-hander Kerber 7-5 6-2 in one hour 19 minutes.
Wozniacki has won 11 of 12 matches on tour since McIlroy sensationally dumped her, with the only blip a tight three-set defeat to world number one Serena Williams in Montreal.
It was not all smooth sailing for the Dane, as Kerber broke serve in the first game of the contest, but Wozniacki returned the favour in the fourth game.
Wozniacki then fended off six break points across her next two service games as she kept her nose in front, before crucially breaking to love in the 12th game to take the opening set.
Kerber barely found rhythm in the second set, getting her serve broken thrice in succession to bow out of the WTA Premier event in underwhelming fashion.
Wozniacki will next face fourth seed Agnieszka Radwanska in the quarter-finals, after the Pole thrashed Germany's Sabine Lisicki 6-1 6-1 in 52 minutes.
Radwanska and Wozniacki have an intriguing head-to-head history - the Dane leads 5-4 - but the Polish world number five has won their past three meetings.
Top seed Williams cruised into the last eight with a 6-2 6-2 victory over Italian 13th seed Flavia Pennetta, and the American will next take on Serbia's Jelena Jankovic.
Jankovic, the eighth seed, got past American Sloane Stephens 7-6 (7-4) 6-4 in a clash lasting over two hours.
Ana Ivanovic joined her compatriot in the quarters, after the Serbian ninth seed got the better of Russia's Svetlana Kuznetsova 6-2 2-6 6-3.
Next up for Ivanovic is Ukraine's Elina Svitolina, after the teenager upset Spanish 15th seed Carla Suarez Navarro 4-6 6-4 6-4.
The other quarter-final will pit second seed Simona Halep against fifth seed Maria Sharapova, in their first match since playing off in the French Open final.
Russia's Sharapova - who lifted the Roland Garros title - downed compatriot Anastasia Pavlyuchenkova 6-4 7-6 (7-2), while Romanian Halep beat Czech 16th seed Lucie Safarova 6-4 7-5.