Air was first to depart after failing to impress presenter Marco Pierre White following the stars' initial culinary task.
The remaining celebrities were then challenged to each cook a three-course menu for 25 paying customers. All three competitors faced a score out of 100, which was determined by the diners and White.
Grant exited after scoring 35 points, below Stephenson's 46 and Rives's 70. White then chose Rives to progress because of her "hard work".
"I feel happy, I feel pleased, I feel relief. It's a great feeling," she said following her win.
Rives now joins Alex Ferns in the final, which airs next Friday at 9pm on ITV1.