In 1989, Baszucki, together with his brother, Greg Baszucki, founded the company Knowledge Revolution following the development of their educational application Interactive Physics. Originally released for Macintosh computers, Interactive Physics was an award-winning engineering simulation software product that allowed users, primarily teachers and students, to create their own physics experiments in a 2D laboratory environment. As a follow-up to Interactive Physics, Knowledge Revolution launched the mechanical design software Working Model in the early 1990s. Similar to its sister program, Working Model also provided a set of virtual mechanical components, such as springs, ropes, and motors, that could be used to create basic physics simulations in a 2D working space. In December 1998, Knowledge Revolution was acquired by MSC Software, a simulation software company based in Newport Beach, California, for $20 million. Baszucki was named vice president and general manager of MSC Software from 2000 – 2002, but he left to establish Baszucki & Associates, an angel investment firm, from 2003 - 2004.
In 2004, Baszucki, along with Erik Cassel – who worked as Baszucki's VP of Engineering for Interactive Physics – began working on an early prototype of Roblox under the working titleDynaBlocks. It was later renamed Roblox, a portmanteau of “robots” and “blocks” in 2005. The website officially launched in 2006. Headquartered in San Mateo, California, Roblox Corporation provides a platform that allows users to design their own games and play a wide variety of experiences developed by other users through its proprietary creation engine Roblox Studio. In a June 2016 interview with Forbes, Baszucki stated that the idea for Roblox was inspired by the success of his Interactive Physics and Working Model software applications, especially among young students: “Seeing how kids lit up when they were creating things using our physics software made me think of what would be the ultimate platform for our imagination. Also I like construction toys and I saw the direction 3-D rendering was going. It became clear to me that there was an opportunity to create an immersive, 3-D, multi-player platform in the cloud where people could imagine, create, and share their experiences together.” A December 2017 study conducted by media measurement and analytics company Comscore showed that the platform saw more monthly hours from visitors under 13 on desktop computers than YouTube. Additionally, the study states that Roblox also received more average monthly visits from users under 18 on desktop computers than YouTube and Netflix. In a December 2016 interview with VentureBeat, Baszucki said, “We believe we’re starting to see a network effect. Retention is getting higher as more people come to play with their friends and have a better chance of finding their friends.” During an April 2018 entrepreneurial thought leadership talk at Stanford, Baszucki attributed Roblox’s growth to its adherence to platform principles: it allows users to create viral content that attracts other people to the platform and it enables creators to drive the monetization. Baszucki believes that Roblox is ushering in a new “human co-experience” category that will become larger than gaming. In a September 2018 interview with Forbes, Baszucki said, "Right when we started, we imagined a new category of people doing things together. A category that involved friends, like social networking; a category that involved immersive 3-D, like gaming; a category that involved cool content, like a media company; and finally a category that had unlimited creation, like a building toy.”