The proposal was captured on camera when singer-songwriter Cline got down on one knee on Friday night at a bar and grill in Panama City, Florida.
In video obtained by TMZ, the 42-year-old Orange Is The New Black star could be seen overcome with emotion covering her face with her hands as the musician popped the question mid performance.
Cline - who is 15 years Manning's junior - was on stage in the middle of a song when she paused and hopped down into the crowd to get down on one knee.
She presented Manning with a ring in a box and the actress eventually said yes after being left speechless.
After the big moment, the DJ got on the mic and told everyone to give the newly engaged couple a hand and the crowd erupted in applause.
It's not known how long Manning has been dating the singer, who fronts band Cline Street, but they were pictured out together in March this year.
A rep for Manning told TMZ that the couple are thrilled and the actress said it was 'the easiest YES' she has ever said.
Manning was a series mainstay of OITNB, appearing in all seven seasons of the Emmy Award-winning series over the course of its six year run from 2013 to 2019.
She played the somewhat lovable crackhead Tiffany 'Pennsatucky' Doggett on the female ensemble show.
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