Costanzo was born in Brampton, Ontario - Canada. His mother is a singer-songwriter and his father an artist. Costanzo is of half Italian ancestry.
Paulo Costanzo's career rapidly grew in 2000 when he landed the role of Rubin Carver in the DreamWorks hit college comedy, Road Trip. This project was soon followed by a supporting role in Miramax Films' 40 Days and 40 Nights, in which he starred opposite Josh Hartnett. He was also seen in Josie and the Pussycats, A Problem with Fear, and opposite Woody Harrelson and Alicia Silverstone in Scorched.
In 2006, Paulo made the move to independent features, starring in the Douglas Coupland-penned comedy, Everything's Gone Green, as a twenty-something slacker suffering through a quarter-life crisis. The film won Best Picture at the 2006 Vancouver International Film Festival.
In 2008, Paulo starred in the critically acclaimed independent horror film Splinter as Seth Belzer. The film won six Screamfest Awards, including Best Picture of 2008.
Paolo Costanzo can currently be seen as Evan Lawson in USA Network's original series, Royal Pains.