Do the Mormons believe The Book of Revelation is a book of the Bible?

No. Members of the Church of Jesus Christ of Latter-day Saints (the "Mormon" church) believe that the Book of Revelation is a very important part of The Bible. Joseph Smith, the founder of the Church, stated that the Book of Revelation was "one of the plainest books God ever caused to be written" and strongly encouraged that it be studied. Among Mormons, the Book of Revelation is probably studied and quoted more than the Epistles of Paul.

The Church of Jesus Christ of Latter-day Saints accepts and uses all the books in the standard King James Version of the Bible, although Joseph Smith said that "the Songs of Solomon are not inspired writings."