Rancic, who won the first season of NBC's "The Apprentice," said his contract with Trump to oversee construction of the 90-story Trump International Hotel and Tower in Chicago will end in March.
"That will probably be it for me," Rancic said late Wednesday during a global leadership forum in Malaysia.
"I'm going to go out and start another business of my own," said the former Internet entrepreneur. "That's in my blood."
But Rancic said he won't totally sever ties with Trump, noting there are plans for him to make appearances in the upcoming fourth and fifth seasons of "The Apprentice," in which contestants use their business savvy to compete against each other, and the winner gets a job with Trump.
Rancic, from Chicago, acknowledged that he would be leaving before Trump's project along the Chicago river is completed. Construction began last October on the glitzy structure, which is to include 227 hotel guest rooms and suites.
Rancic, whose victory on "The Apprentice" debut season finale was watched by 28 million viewers in the United States, said he was currently also involved in a fruit processing operation in Canada and was exploring other business opportunities, particularly in real estate.
"In the years to come, I hope there will be Bill Rancic towers right alongside the Trump towers," Rancic said.
He voiced confidence about his post-Trump future, saying he has learned "powerful lessons" and made valuable contacts.
"Donald Trump has taken me under his wing," Rancic said. "I've gone all over the world with him, I've seen every deal that he's involved in right now. I've really seen what business is like on one of the highest levels out there."
Rancic, 33, urged Asian entrepreneurs to emulate what he called Trump's boundless passion for work.
"He's a guy who's going to die in that chair, putting together some big deal," Rancic said. "I don't think Donald Trump will ever stop. He truly loves what he's doing."