The Hunger Games actor, 30, and model girlfriend, also 30, dressed up as Peaky Blinders characters alongside brother Chris Hemsworth and wife Elsa Pataky, parents Craig and Leonie and Luke's wife, Samantha, to celebrate Luke turning the milestone age.
The Thor actor, 37, shared a photo of the family via his Instagram page over the weekend. "Happy 40th birthday @hemsworthluke you big legend !!" he captioned the pictures of the crew.
A few days prior to the festivities, Liam shared a photo of the three brothers via his Instagram. "Happy 40th birthday @hemsworthluke ! You've been a wonderful brother all these years. I've taught you well...the rest is up to u. Love ya Luke!" he wrote alongside the selfie.
"Thanks @liamhemsworth," Luke commented on the touching post. "You'll always be the little brother whos best at crying! Love ya forever."
Liam and Gabriella first linked up in December of last year — four months after his split from ex-wife Miley Cyrus. "He feels more at home with Gabriella than he did with Miley and feels like he can be his complete self without any drama," a source previously told UsWeekly. "Gabriella helped Liam boost his confidence and played an encouraging role in his life after his split with Miley. They are very happy together and it's comfortable and easy."
The source further explained that "Liam's family really likes Gabriella for him. She understands Liam's values as well as his family's, which is something that's very important to him and them." The Australian love birds have been "going strong" as they spend time in Byron Bay, Australia, amid the COVID-19 pandemic.
"Liam is happy to have moved on and is living a completely different life now," another source noted of his time spent in Australia with Gabriella and family. Liam's older brother Chris also moved back to Byron Bay with his wife and three children — India Rose, 8, and six-year-old twin boys Sasha and Tristan — to live a more peaceful and laid-back lifestyle in their $20M estate.
Liam and Cyrus, 27, tied the knot in December 2018 and split less than eight months later. The former flames announced they were parting ways in August 2019 after 10 years of being in an on-again, off-again relationship. Despite the recent breakup, "Gabriella isn't worried that Liam has any lingering feelings for Miley and isn't intimidated by their relationship," the source dished.
"Liam and Gabriella are really close and feel comfortable with one another," they added. "They connect over important topics and share the same values about family and life."