The E! News anchor and managing editor - who also hosts Fashion Police and Live From the Red Carpet - has agreed to stay with NBCUniversal's channel until at least April 2015.
The network will also get first refusal on Rancic's ideas for new programming.
Rancic - who is expecting a child via gestational surrogate with husband Bill Rancic - told The Hollywood Reporter: "It's been an amazing ride, and I'm excited for my journey at E! to continue.
"I'm extremely proud of the tremendous opportunities E! has given me over the past 10 years, and I'm excited to be part of the network's exciting future. The best is yet to come."
E! president Suzanne Kolb said: "Our viewers feel a special connection to Giuliana, since in many ways she's grown up on our air over the past decade.
"Giuliana's on-air charm, charismatic personality and outstanding professionalism have made her one of TV's most recognised hosts, and her work has helped propel E! News to new heights."