The two, who have an 18-month-old baby named Tripp, say they're engaged. Palin, the daughter of 2008 vice-presidential candidate and former Alaska Gov. Sarah Palin, is featured on the cover of Us Weekly with Johnston, holding Tripp.
"We got engaged two weeks ago," Bristol, 19, told Us Weekly. "It felt right, even though we don’t have the approval of our parents."
Sarah and Todd Palin released a statement on "Good Morning America" that read like a rather tepid congratulations.
"We obviously want what's best for our children,” the couple said. “Bristol believes in redemption and forgiveness to a degree most of us struggle to put in practice in our daily lives. We pray that, as a couple, Bristol and Levi's relationship matures into one that will allow Tripp to grow up graced with two loving parents in his life.”
The pair began dating as high school freshmen, and were previously engaged. They broke it off in March 2009, enduring a bitter public breakup in which Johnston trashed the Palin family in tabloids and went on to pose in Playgirl, which drew the scorn of his future in-laws. But in recent weeks, the pair were known to be warming up to each other for the sake of their son.
The pair say they reconnected while working out a custody plan and became engaged two weeks ago.
"I really thought we were over," Johnston told the magazine. "So when I went, I had no hope. I think we both just started talking — and then we took Tripp for a walk."
Johnston, 20, has apologized for disparaging comments about the Palin family and said he was lying when he characterized Sarah Palin, who has taken to calling herself "Mama Grizzly" on the political trail, as a phony and a lousy mom after he and Bristol broke up last year. He says he has apologized to them.
Since her pregnancy was made public during the 2008 presidential campaign of John McCain and her mom, Bristol Palin has become a public speaker and advocate for teen abstinence. Earlier this month, she played herself in a guest appearance on ABC Family's teenage drama, "The Secret Life of the American Teenager," a series which focuses on a family dealing with a 15-year-old's unexpected pregnancy.
Johnston, a high school dropout who has worked as an apprentice electrician, has been trying to launch an acting career.