In addition to Georgie Gardner and Deb Knight leaving the show, Channel Nine reported entertainment guru Richard Wilkins and weather presenter Steve Jacobs will also depart.
New recruits include Tracy Vo, who will join the team as a newsreader, while Tim Davies joins as a weather presenter and Alex Cullen joins as sports presenter.
Brooke Boney will continued her role as entertainment presenter on the program, while Richard Wilkins will host Weekend Today alongside Rebecca Maddern.
Jayne Azzopardi will continue to present news on Weekend Today until she goes on maternity leave, at which time Lara Vella will cover.
With Sonia Kruger no longer part of Today Extra, Sylvia Jeffreys will continue to co-host alongside David Campbell, until she goes on maternity leave and Belinda Russell covers.
Channel Nine’s Director of Morning Television Steven Burling said Karl and Alison’s experience in the industry will be of great benefit to the future of the program.
"Ally and Karl are quite simply two of the best news broadcasters in the country. Both have reported from conflict zones, they are more than comfortable going toe-to-toe against our most formidable politicians and quite honestly they're who you'd turn to in times of breaking news, be it here in Australia or anywhere in the world," Steven told the network.
"Importantly though, Ally and Karl also know how to have a good laugh, they both have an infectious, self-deprecating sense of humour that I believe will resonate with viewers and the rest of the on-air team.”