Everyone expected The Block's grand finale to be full of surprises... but perhaps not a romantic surprise, as Josh proposed to Jenna prior to the auction.

Earlier in the night at the pre-auction cocktail party the couple seemed a little nervous, but happy and wrapped up in the excitement of the night. Then, as the auction was about to get underway, the hall of bidders looked up at a screen and saw Josh pulling a small blue Tiffany box out of his pocket and get down on one knee.

"As you may have just seen, Josh has just proposed to Jenna!" host Scott Cam confirmed to the audience. "So his nerves were not just about the auction."

Jenna was all smiles and wiped some tears as she opened the box and put the ring on her finger. The biggest applause and yells came from the back corner of the room where all the couples were gathered to watch Josh and Jenna's house be auctioned.

The couple's tender moment was interrupted as their auctioneer Ruth Robert took to the stage to commence the business end of the evening.