He graduated from the Interlochen Arts Academy and the Cincinnati Conservatory of Music. It was at CCM he encountered future Hi-5 colleague Jennifer Peterson-Hind. After college, he became a broadway sensation, portraying memorable roles as Doody from Grease, Billy from Anything Goes, Dickon from The Secret Garden, and the Pinball Lad from Tommy. The play he is most remembered in is Rent, where he made his Broadway debut. He was also an emcee for the Nickelodeon show at Paramount's King's Island.

In 2003, he joined the American counterpart to the famous Australian kid's show Hi-5. As a member, Curtis was the American counterpart of Tim Harding. In Hi-5, his segment is Making Music, where he would explain the fundamentals of music and making musical instruments from everyday objects. Some or all of his fellow Hi-5 members would join him in singing and playing instruments. Some of his solo songs (or songs where he is the lead singer) includes:

Space Friends Building a Fence My Best Friend (a tribute to his old dog Alfie) Yodel-Moo Chatty Feet Shakers Roller Coaster Let's All Make a Sound I Wanna Be Small/Tall Captain Puffy Pants (a favorite role of Curtis) Where Your Heart Is (a.k.a. Keeper of the Night Stars) (a favorite song of Curtis fans)

Cregan also provides the voice of Kimee Balmilero's mischief-making friend Jup-Jup.

Outside of Hi-5, Mr. Cregan likes to cook, rollerblade, and take long trips on his motorcycle. His favorite animals are dogs and monkeys. His favorite color is green. His favorite musicians are Chet Baker, Miles Davis, U2, Radiohead, and Luciano Pavarotti. His favorite TV show is 24, a favorite of fellow Hi-5 members Shaun Taylor-Corbett and Jennifer Peterson-Hind. His favorite movie is the Lord of the Rings trilogy. He likes to eat pizza and play hockey. In the future, he would like to see what Hi-5 brings to children everywhere.