Kerber and compatriot Beltz first worked together from 2011-13 and rejoined forces in 2015, with the German pair having their most successful season a year later.
"It's been tough but I'm about to start a new chapter in my career, with a new coach," Kerber said on her official Twitter account. "Thank you Torben Beltz for everything that you've done for me.
"The next season is coming soon and I'm very excited to start working with Wim Fissette as my new coach. It's a new chance and I'm curious to find out what we can achieve together."
Fissette has previously worked with top players such as Kim Clijsters, Victoria Azarenka and Simona Halep, and coached Britain's Johanna Konta for the 2017 season before the pair agreed to a mutual split at the end of the campaign.
(Reporting by Aditi Prakash in Bengaluru)
