The 33-year-old singer will open up about his life in the Backstreet Boys, his struggles with substance abuse and his family tragedies, including the death of his sister Leslie from a suspected overdose last year, in `Facing the Music and Living to Talk About It`.
The tome will be published by Bird Street Books on September 24.
Nick proposed to his girlfriend of four years Lauren Kitt, in the Florida Keys with a seven-carat diamond ring from XIV KARATS in February and admitted he was desperate to pop the question.
He said: "I was like, `I don`t want [the ring] anymore!` It was driving me insane. I just wanted to get it out of my hands and on to hers.
"She said, `Yes,` and I`m, like, `I don`t know what to do. She said, `You`re supposed to put it on my finger.` So I did. I was in shock."
Fitness expert and actress Lauren, 29, admitted she was shocked by the proposal and acknowledged wedding dates will have to be worked around the upcoming Backstreet Boys tour.
She said: "I wasn`t expecting it. It just felt very surreal. We both are just so happy in love right now and on cloud nine.
"Our first thought was, `We need to contact the Backstreet Boys and find out when their schedule will permit.
"It`s not up to us. It`s up to the schedule. We`re just excited and looking forward to the next chapter of our lives."