The mother-of-five confirmed the news with a photograph of the couple on her Instagram account, who are seen embracing and smiling at the camera.
"Date night," said the caption, which sparked a flurry of congratulatory comments from Tish and Billy Ray's fans.
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A close family friend, Ken Baker, said the pair had been going to couple's therapy for the first time and it seemed to be working.
"I spoke to Tish and she told me they both woke up and realized they love each other and decided they want to stay together," said Ken, speaking to E!
"Couple's therapy brought them closer together and really opened up their communication in amazing ways. They both realized they didn't want to be another statistic and want to make it work."
Country singer Billy Ray and Tish took time off their relationship just last month, with the mother-of-five filing for divorce. She cited "irreconcilable differences" as the cause for the breakdown of their 19-year marriage.
Tish requested physical and legal custody of the couple's youngest daughter Noah, 13, with visitation rights for Billy Ray. She also sought spousal support and asked that the country singer cover her attorney fees.
This is not the first time the couple have had their differences though. In 2010, Billy Ray filed divorce papers himself but then changed his mind, saying he wanted to "put my family back together".
Apart from Miley and Noah, the couple have three other children together — Brandi Glenn, 26, Trace, 24, and Braison, 19.