The romantic pop star, 21, reportedly dropped to one knee after showing up unannounced at Deleasa's home in New Jersey on Wednesday morning -- after flying in from a Tuesday night concert in Vancouver, Canada.
He presented her with a custom-made, cushion-cut diamond ring, according to People.com.
A thrilled Jonas tells the publication, "It was tough performing last night, knowing that I was going to ask the biggest question in my life to the most amazing girl in the world.
"She said yes, yes, yes, like, 500 times super fast in a row."
The couple met in 2007 while vacationing with their families in the Bahamas, and Kevin has the blessing of his parents.
A statement from Denise and Kevin Jonas, Sr. reads, "Our hearts are filled with joy today and we are happy to share with you that our son Kevin has asked Danielle for her hand in marriage... It is such a blessing that she will be joining our family."
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