Younger star Molly Bernard is engaged to her girlfriend Hannah Lieberman.

The actress, who stars as Lauren Heller in the hit U.S. TV show, announced the happy news on her Instagram page on Tuesday.

"We said YES!" Molly wrote, alongside a picture of herself and Hannah grinning broadly as they posed with their dog Henry.

The 31-year-old's ring could also be seen in the snap - a centre diamond with a half halo.

The engagement news comes just weeks after Molly helped officiate the wedding of her Younger co-star Hilary Duff and Matthew Koma, with actor Christopher Mintz-Plasse referencing the nuptials as he offered his congratulations to the happy couple.

"Are you allowed to officiate your own wedding?! CONGRATS!!" he wrote.

Molly told Entertainment Tonight in 2017 that playing a pansexual character in Younger helped her understand her own sexuality.

"Her confidence has helped me a lot. It helped me in a few different ways: Her confidence helped me with my own kind of nervous and self struggles, but she's also helped me with my sexual identity," she said. "I don't identify as straight."

She explained that while she mostly dates men, "it would be perfectly possible and wonderful to have a (relationship with a) woman or trans person... I've always felt this way, but now it's part of the conversation, we can talk about it. There's language for it."