Since the end of his Brady Bunch appearances, Knight's acting career consisted mostly of making guest appearances on other television shows. He also helped create a Brady Bunch computer game and is involved in the IT industry, according to a TV Land documentary about the Brady Bunch.

He went back to his Brady roots in the 1988 Brady Christmas movie, A Very Brady Christmas.

An interest in science and machines led Knight to a career in the computer industry in 1988. His celebrity status helped him to hone skills in sales and marketing. Entering the industry as an account sales manager at Martec, Inc., he logged the company's first US$1 million sales order within his first eighteen months, quickly becoming Martec's top performer and employee of the year.

In October 1989, Knight became vice president of design system marketing and sales at New Image Industry, moving the company into 3D rendering/imaging technologies. Then in mid 1991, he, and a few other key employees successfully moved the software engineering staff and the 3D technologies into a new privately held company, Visual Software. As co-founder of Visual Software, Knight was an early participant in the consumer 3D graphics market. His efforts led to business success, seeing the company move from $400,000 in annual sales to $4.2 million within 10 months. Visual Software was acquired by Micrografx in January.

In late 1995, Knight partnered with friend and associate Frank Paniagua, and founded Kidwise Learningware, a producer of interactive edutainment products for children. Knight served as executive producer.

In February 1996, he became the vice president of sales at Adesso, a computer keyboard manufacturer. Within his first 4 months sales doubled.

Knight and Paniagua reunited in August 1997 at Integrated Micro Solutions (I.M.S.) which later became IXMICRO. Initially hired as vice president of strategic marketing, Knight was promoted to vice president of marketing four months later. Annual sales went from less than $2 million in early 1997 to $63 million in 1998. Also brought in was Jim Pilgrim, known for engineering related sales in the market, Knight and Pilgrim connected on many projects at IXMICRO.

In late 1998 Knight, Paniagua and an associate, David Smith, formed Eskape Labs. The three had been part of IXMICRO's executive staff, but sensed a shift in the focus of computer technology from personal computers to intelligent devices. With a mission to provide "on wire" digital appliances that easily plug into computers, Eskape has developed a number of first-to-market video devices. The company was purchased by Hauppauge Computer Works in the summer of 2000. Hauppauge is the world's largest manufacturer of computer based TV tuner products and, with Eskape Labs, now has a line of TV tuners that are Macintosh compatible.

Knight appeared on a special episode of The Weakest Link TV show that featured the cast of the Brady Bunch squaring off against each other. In the end, Knight won the show with the proceeds ($49,000) going to his selected charity, Zero Population Growth.

Continuing to pursue TV opportunities, Knight appeared on VH1's fourth season of The Surreal Life. The show garnered Knight more attention than he had received in quite some time, in part by appearing shirtless on the show and revealing a well-built body. During his stint on the show, he began a romance with a castmate, model Adrianne Curry, winner of America's next top model cycle 1, who is almost 25 years younger than Knight. After the show, the two moved in together and got engaged, as documented on the VH1 series My Fair Brady, which premiered on September 11, 2005. The series was renewed for another season, and the couple wed in Curry's hometown of Joliet, Illinois on May 29, 2006 in a Gothic style wedding.