Kramer's professional acting career started in the late 1970s, while she was still in school. She guest-starred in several television shows, such as Starsky and Hutch, Dynasty, Bosom Buddies, and Knots Landing. Kramer graduated from the American Academy of Dramatic Arts/West, where she has later taught as a guest instructor. Kramer starred in the NBC sitcom We Got It Made in 1983. Her big break came in 1984, when she landed a starring role in Hunter, a creation of television mogul Stephen J. Cannell. After a rough start, the show became an international hit, and was broadcast for seven consecutive seasons. Kramer starred in six of them, appearing in a total of 130 episodes. In an interview with Jay Leno in 1989, Kramer admitted that she had not believed the show would be as long-lived as it was.

In 1986, Kramer stated she was working on a rock album with Composer Mike Post, who had penned music for Hunter. She also announced that she might put out an album the following year. No album was forthcoming, though, and in 1990, Kramer announced her departure from Hunter. The press claimed it was to concentrate on her music career, and in a television news interview, Kramer stated "I have been most fortunate in that I've acted, written, and directed while on Hunter. It is time for me to move on to the next phase of my life, both professionally and personally."

Kramer has continued to work as an Actress. After her departure from Hunter, she appeared in several TV shows and movies. Her most notable movie projects include: Twin Sisters (1992), Beyond Suspicion (1994), The Dogwalker (1999), and The Cutting Edge: Going for the Gold (2006). She also reprised her role as Dee Dee McCall in the two Hunter television movies (2002 and 2003). Because of their strong ratings, NBC attempted to bring the television show back, but the 2003 revival was canceled after only three episodes.

Shortly after leaving Hunter, she began recording an album in England with Producer Nils Lofgren. The album was never released. In 1992, Kramer married and moved to Colorado. Two years later, she gave birth to a daughter. She continued to write music and star in successful made-for-TV movies and indie films. She is a trained mezzo-soprano, and during the hype of her TV career, she had showcased her musical abilities on several episodes of Hunter, as well as on Bob Hope television specials. Stepfanie's first album came out on October 12, 1999. One Dream contains 10 adult contemporary songs. Most are original songs which prove Kramer's talent as both a Composer and lyricist. The Great American Song Book, her second album, came out early in 2008. On it, Kramer covers 14 classic songs recorded live in a one-woman show which she performs in various national venues. In 2008, she represented the U.S. by performing at the International Music Festival in Queretero, Mexico. As a singer, she has performed around the globe.