After 14 years with the show, Rancic, 40, is moving on but will remain with E! as the host of Live from the Red Carpet and co-host of Fashion Police.
"I knew this day would be bittersweet but I was not prepared for how incredibly special it would be," Rancic told PEOPLE exclusively on Monday night, shortly after taping her last show. "I am lucky to have worked side-by-side with some of the most talented and kindest people in the business who gave me the most loving send-off I could have ever hoped for. I cried tears of joy but today feels like my graduation day and I can't wait to write my next chapter."
It's been a rollercoaster year for Rancic, who came under fire in February for comments she made on Fashion Police about singer Zendaya. The controversy led to a public spat with co-host Kelly Osbourne, who left the show, and the subsequent departure of Kathy Griffin.
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Rancic told PEOPLE last month that the decision to leave E! News was "100 percent" hers.
"After 14 years, I have nothing else to accomplish on the show," she said. "I want to grow as a person, as a businesswoman, as a host, and in order for me to grow, I need to take on a new venture and new challenges."
The cancer survivor has moved full-time to Chicago with her family – husband Bill Rancic and their son, Duke, 3.
"I'm looking forward to being able to stay in bed a little longer with Duke every morning and take him to school and on play dates!" she said.
Bill, 44, who was in the studio for her final taping on Monday, wrote an open letter to his wife as she embarks on this new phase of her life.
"You've won in life. I mean that," he wrote. "You've evolved, you've matured and you influenced others around you to do the same. You've inspired others and it shows. But there's more adventure to be had. There's bigger and better things out there."