The siblings from New South Wales went head-to-head against Megan Woodman and Andy Appleby in a sudden death cook-off as part of the Australian reality TV show's special elimination week.
Steve and Helen prepared a rolled chicken dish with Greek cheese sauce and spinach rice and scored 36 out of 60, but failed to beat Megan and Andy's 50-point jambalaya.
Judge Pete Evans told the eliminated couple: "It is with great sadness we have to say goodbye to you. You were the first cab off the rank with your instant restaurant, and ever since then it's been so much fun getting to know you both.''
Helen described her My Kitchen Rules experience as "amazing", saying: "We've been sad and happy; it's brought out the best in us.''
Steve added: "I'd like to thank my sis for bringing me into this competition. The biggest highlight was cooking for two renowned chefs. We've made my parents, grandparents and fellow Cypriots proud.''
Megan and Andy have now made it to the final, along with South Australians Leigh Sexton and Jennifer Evans, Nic Mazzone and Rocco La Bella and sisters Carly and Emily Cheung.
My Kitchen Rules finals start tonight (March 22) at 7.30pm on the Seven Network.
> Logie Awards 2012 nominations in full
> 'MasterChef' to 'My Kitchen Rules' boss: 'There's room for both of us'
Watch a round-up video of Helen and Steve's time on My Kitchen Rules below: