Brook’s career had stalled after a fruitless jump to middleweight to challenge Gennady Golovkin in September, 2016 while a drop back down to welterweight last May saw him lose his IBF crown to Errol Spence Jr.
But he drew a line under those twin defeats in emphatic style by ending the challenge of the rugged Rabchenko within five minutes to send a warning to the top tier of 154lb fighters.
He said: “I’m putting the champions on notice. I’m here and I felt good, anyone getting hit with those (punches) and it’s game over.
“I’m aiming for the stars. I’m going to go out and win another world title, you’re going to see me perform like this every time.”
A showdown with long-term rival Amir Khan, who is now under the same Matchroom promotional banner as Brook, has also been mooted in recent weeks.
Brook added: “I’ve got no message for him except to just enjoy his training and get his wins. That’s how me and him are going to happen, we’ve both got to keep winning and it’s going to naturally come together.”
Brook feels galvanised by the move to light-middleweight, having decided to go up a division following his much-publicised struggles to make the welterweight limit.
His initial foray proved spectacular against a fighter who had lost only twice in his previous 31 professional outings and who, Brook says, gave him some tough sparring sessions in the past.
But the Belarusian was unable to hit his stride against Brook, who, backed by a buoyant crowd in his home city, wasted little time settling into his stride behind a crisp jab.
The 31-year-old landed many thudding combinations in the opening round before stepping up his attack in the second, with a bruising right uppercut followed by a right to the temple that put Rabchenko on the mat.
Rabchenko was unsteady as he attempted to rise and was counted out just before referee Steve Gray called a halt to proceedings after one minute and 27 seconds of the second round.
Brook said: “I felt good once I got settled, the timing came and the uppercut set everything up and we finished the fight. Obviously I’ve been out and it’s good to get the first tick back and just get settled.
“I felt strong at the heavier weight. The weight’s a big thing, imagine taking another seven pounds off me!
“I just felt a lot healthier and when you’re getting older (trying to lose weight) takes it out of your legs and body, it’s like taking weight off a stone, there’s nothing to take off me.
“You can probably get away with it in your 20s but it’s so draining (now). It’s a big difference.”