Dalton, 29, posted the same snap, also captioning it with a silly message. "Just got served a life sentence," she wrote.
The proposal happened on Monday, July 16, at Six Mile Lake in Muskoka, Ontario, ET has learned. Hinchliffe got the ring from Knar Jewellery in Oakville, Ontario. No one, save for his parents, Arlene and Jeremy, as well as the jewelers, knew the proposal was happening.
"Literally only four people in the world knew this was happening: my parents and the jewelers," Hinchcliffe tells ET of how he popped the question. "After the Honda Indy Toronto, we headed to our cottage in Muskoka and I had it all planned out to ask her to go on a booze cruise after dinner. While we were driving up to the cottage, it was cloudy and not looking great out, but as we got closer the weather broke. After we made dinner, I ran over to my parents’ cottage telling Becky I was grabbing the boat keys, but really the ring was there, along with some champagne. I stashed them on the boat, and when we got to a place where we were just enjoying the moment, I got up and grabbed the ring from the glovebox. I got on one knee and asked Becky to marry me."
"Somewhere amongst the ugly cries there was a yes and there you have it!" he added. "When we made our way back to the cottage, my parents had 'When a Man Loves a Woman' blasting with candles lit around our cottage."
The bride-to-be tells ET that the proposal took her completely by shock.
“I was completely surprised! Honestly, I thought he was ruining our moment [enjoying the peace and quiet on the lake] because he got up and I thought he was going to start the boat back up," Dalton tells ET. "He got on one knee and then I started ugly crying! He even hid a bottle of champagne on the boat along with the ring. I really had no idea."
Last summer, Hinchcliffe stopped by ET's Los Angeles studio for a Facebook Live interview to reflect on his time on season 23 of Dancing With the Stars with his pro partner, Sharna Burgess. At one point during the chat, he couldn't help himself from gushing over Dalton, teasing that an engagement was "on the horizon."
"No immediate plans," Hinchcliffe said at the time. "But you never know!"
Hear more from the exclusive sit-down below:
We're LIVE with IndyCar driver and Dancing with the Stars Season 23 Runner-up James Hinchcliffe!