Cyrus and Hemsworth dramatically split in 2013, three years into their relationship and were apart for three years. Cyrus was devastated by the break-up and threw herself into a wild party-girl lifestyle.
They originally met on the set of the movie, The Last Song and became engaged when Cyrus was aged just 19.
Hemsworth was a virtual unknown and Cyrus was a Disney pop princess.
At the time of their 2013 split, Cyrus was radically overhauling her squeaky clean teen star image.
Miley and Liam first met on the set of Last Song in 2009.
Her raunchy act with Robin Thicke at the MTV Music Awards in August 2013 closed the door on Hannah Montana forever.
In a performance described as "cringe-worthy", Cyrus bumped and grinded against the older star after touching his crotch with a large foam hand.
She then performed her infamous "twerk", a sexy move that went viral and shocked fans.
A month later, the star announced she had split from Hemsworth.
Three years later, in 2016, she and the Aussie hunk reconciled. Cyrus said goodbye to her Bangerz-era image and released music with a more country feel.
In separate interviews, the star couple revealed the reason for their shock split. And it was all very mature — they both needed to grow up.
In an interview with Howard Stern in 2016, Cyrus said the split was essential for her personal growth.
"I had to. I don't like when relationships are two halves trying to make a whole,' she told the radio presenter.
"So, I don't think that I have that co-dependency," she added. "I think people that break up and get back together, that's awesome.
"You get time to be yourself. You get time to grow up. I think if you're growing up attached to another person, you never really get solid as your own being."
Hemsworth was even more frank about the split, telling GQ Australia in 2016: "Of course it was hard, man. But at the time we were going in different directions and it's just what needed to happen."
At the time of the interview, the couple had just reunited and Cyrus had started wearing the Neil Lane 3.5 carat diamond ring Liam presented her with, in May 2012.
Robin Thicke and Miley Cyrus perform during the 2013 MTV Video Music Awards. Photo / Getty
"We were both super young and it was a good decision at the time – we both needed that."
Addressing their on-off relationship, Liam said: "I guess when I feel something, then I just feel it and I go for it.
"I make my decisions about what's going to make me happy, what I think is right and what I want to do – and I don't worry too much outside of that."
After their recent marriage, a friend of Cyrus told People magazine the pair had "evolved".
"Miley and Liam's relationship has evolved so beautifully over the past few years. They first grew as individuals and ultimately evolved as a couple.
"It speaks to who they are and their mutual respect for one another."
An insider close to the singer told People their marriage was brought on by the loss of their Malibu home during the California wildfires last year.
"They don't have doubts about their relationship," the source said. "They both wanted to get married. They have both matured a lot, and it seemed like the perfect time for them to get married."