Pennington was considered an unruly child and had difficulty performing throughout school. It wasn't until he was seventeen years old that he was tested for and diagnosed with Attention-deficit hyperactivity disorder (ADHD). He is now a spokesperson for the organization ADHD Experts on Call, and manages his condition with Adderall XR. Additonally, his mother, Dr. Yvonne V. Pennington, is a psychologist who focuses on the treatment of ADHD and depression. He is generally considered a good host, constantly positive and supportive of the clients of the show.

A self-described "Jack of all trades," Pennington learned woodworking early in life. He received his undergraduate degree in graphic design from the Art Institute of Atlanta while working his way through school as a carpenter, and continued to work in carpentry after graduation while taking classes in painting and sculpture at the Atlanta College of Art. During his final semester, Pennington was approached by a modeling scout, and soon began a lucrative career. He traveled the world and landed print jobs for J.Crew, Swatch and Sprite, and appeared in television spots for Diet Coke, Levi's, and Macy's, among others.

Pennington parlayed his hands-on skills and design acumen into a career in the entertainment industry, becoming a set designer, including for the critically acclaimed film Leaving Las Vegas in 1995. However, his professional breakthrough came through The Learning Channel's innovative hit show Trading Spaces . He quickly became known for his off-the-wall sense of humor and creative style during four years as the show's playful designer and carpenter.

When ABC began developing a show that would transform the homes of deserving families in seven days or less, Pennington was chosen as the leader of the eight-man design team. "Extreme Makeover: Home Edition" went on to be a huge hit, and catapulted Pennington into the mainstream. This led to an endorsement deal with Sears, a sponsor of the show. In January of 2005, Pennington fell ill and underwent an emergency appendectomy, taping an episode of Extreme Makeover: Home Edition while in the hospital.

Prior to his partnership with Sears, Pennington was the owner and designer of his own online furniture company, Furniture Unlimited. Today, however, he lends his design skills to Sears, personally guiding the design of every item in the Ty Pennington Style line of bedding, tabletop items, and bath accessories. In addition to his involvement in design, marketing promotions and public relations activities for Sears, Pennington is also active in community outreach through the Sears American Dream Campaign.

Pennington is also an author, who (in 2003) published the book Ty's Tricks: Home Repair Secrets Plus Cheap and Easy Projects to Transform Any Room, a do-it-yourself guide on home improvement.