The former Hawks president and ex-Victorian Premier, a vehement critic of the league, called the AFL inept and added the club had not lobbied publicly to continue the agreement.
He said ending Hawthorn's 25-year deal to play some home games in Launceston would cost Tasmania at least $40 million per season.
Hawthorn's current deal to host four home matches in Launceston runs until the end of 2027.
The AFL told Hawthorn on Monday night the deal would not continue once the Tasmania Devils became the 19th team in 2028, so the new side could become the "primary focus" for football in the state.
While current Hawks president Andy Gowers said he was disappointed but not angry, Kennett predictably took a sharper tone.
"I'm very disappointed and I'm angry - the club did not fight for this publicly," Kennett told AAP.
"They may have been having quiet discussions with the AFL. The AFL have simply run over Hawthorn and treated them with great disrespect.
"The AFL have also made a mistake, because they show no respect for Tasmania or understand the Tasmanian community. Yes, the Tasmanian community want the Tasmania Devils, but the reality is Hawthorn used to bring in $40 million a year.
"What is terribly upsetting about all of this is that the people of Launceston, who looked after us as a full partner for so long, have been totally ignored in this whole equation."
Kennett, a long-time passionate supporter of the Launceston deal, pointed out South Australia, Western Australia, Queensland and NSW all had two teams.
"Once again, the AFL is proving itself to be absolutely inept and Tasmania will pay a high price," he said.
"The AFL has totally misunderstood the economics and emotions of the decision.
"I'm angry at the Hawthorn board, who failed to conduct any public advocacy for Tasmania, for our club and for its membership in Tassie."
Hawks coach Sam Mitchell felt the decision was like being kicked out of home.
Hawthorn said in a statement they were "extremely disappointed". Gowers said the club lobbied hard for the agreement to continue beyond the Devils joining the league, arguing the two teams could co-exist.
"You know the people at the coffee shop, the hotels and you go on the same sorts of walks ... it feels like we're being kicked out of a home," Mitchell said.
"I understand I guess from the AFL's perspective ... (but) enormously disappointed."
Gowers said the success of Hawthorn's Tasmanian deal had been unprecedented in the AFL.
"It makes sense to the AFL. It's what they have decided," he said.
"We've never seen a partnership of this length in another state before, have this kind of success.
"Today is a moment in history. Disappointed ... but we think we can be stronger as a result."
Gowers added Hawthorn would lobby for their four Launceston games to be moved to the MCG.
He also said the club would speak to the AFL about financial compensation, given the reduction in revenues it would cause.
Hawthorn also have built a distinct home-ground advantage in the northern Tasmanian city.
"Obviously we love playing there, we feel like we do have an advantage," said Mitchell, who also played in Launceston.
But the AFL on Tuesday confirmed Hawthorn would "transition out" of Tasmania after next season, paving the way for the Devils to be the "primary focus" for football in the state.
"The AFL acknowledges and thanks Hawthorn for its outstanding contribution to footy in Tasmania," AFL chief operating officer Tom Harley said.
"With the Tasmania Devils entering the AFL competition in 2028, it is appropriate that the Devils become the primary focus for football in the state, giving Tasmanians their own team to support on the national stage."
Hawthorn will play the second of four games in Launceston this year when they host Adelaide at UTAS Stadium on Thursday night.
Hawthorn have a remarkable 76 per cent winning record in Launceston from 87 games.
Mitchell's team are on an 11-match winning streak at the venue, formerly known as York Park.
North Melbourne had a similar deal with Tasmania in Hobart before it ended in 2025.
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