Combs, 36, and Porter, 35, announced the pregnancy last month. They have an 8-year-old son Christian, and Combs has a 12-year-old son Justin from a previous relationship.
In an "emergency announcement" video posted Monday on his Myspace.com page, Combs (shown outdoors, flanked by the glamorous Porter) broke the news. "Two more Combs. Two! World, you're in trouble now," he said, calling himself a "champion."
The couple learned of the double pregnancy during a recent trip to the doctor after Combs became concerned that Porter "looked kinda big for the amount of months she is."
"The doctor told me and Kim, and I'm telling you right now, no press announcement, I'm just telling people in my family, that I'm having twins. It is official," he said.
His new album, "Press Play," is slated for release in October.