Rinearson began his career as a journalist at the Seattle Times, winning a Pulitzer Prize (for a series on the Boeing 757) and the ASNE Distinguished Writing Award before he was 30. His series on the 757 has been excerpted in several books on journalism and writing. Other first-place national awards included the Lowell Thomas Award from the American Society of Travel Writers (judged by the University of Missouri School of Journalism), in recognition of Rinearson's consumer affairs coverage of air travel, and the John Hancock Award for business writing, in recognition of his coverage of Japan. Rinearson was a national semifinalist for the Journalist-in-Space project, which NASA cancelled following the Space Shuttle Challenger disaster. In college, he won the national writing championship in the Hearst Journalism Awards Competition. He is a former member of the National Advisory Board of the Poynter Institute, a leading educational institution for working journalists, and he is on the Visiting Committee of the University of Washington Department of Communications, from which he holds a bachelor's degree.
Rinearson co-authored Bill Gates' first book, The Road Ahead, which was No. 1 on the New York Times bestseller list for seven weeks in 1995 and 1996. Rinearson and Gates were joined in their effort by Nathan Myhrvold, who at the time was Microsoft's chief technical officer.
In the 1980s, Rinearson wrote the leading books on how to use Microsoft Word for DOS. He created the first software disk to accompany a Microsoft Press book, which presented a system of styles and style sheets that Microsoft later commissioned him to revise for Word for Windows. This work laid the foundation for the formatting styles built into Word today.
In 1988, Rinearson founded Alki Software Corporation, the first company devoted exclusively to providing third-party solutions for users of Word. With Alki Software, Rinearson conceived several aspects of Microsoft Word, including its first table feature, and designed the first toolbar for Word for the Macintosh, which was subsequently licensed by Microsoft from Alki. From 1990 until 2002, Alki Software published and sold Microsoft Office Proofing Tools.
In the latter half of the 1990's, Rinearson spun off from Alki an Internet company called InType, which created tools for Web-site publishing and developed sites aimed at parents. He sold InType to Oxygen Media in 1999. Among the assets Oxygen purchased was Babynamer.com, a site that Rinearson built after pondering names for a child of his own.
In 1995, Rinearson co-founded Raster Ranch Ltd., a digital design company that counted Microsoft, Walt Disney Co. and HP among its repeat customers. Raster Ranch closed in 1999, when its employees transferred to Oxygen Media.
From 1999 to 2001, Rinearson was a senior vice president of Oxygen Media, a cable-television network oriented toward women.
From 2002 until late in 2004, Rinearson was a Microsoft corporate vice president. He was a member of the senior leadership team of the Information Worker Business Unit, which publishes Microsoft Office and other productivity tools. He established and ran the New Markets division, where he was responsible for incubating new products and services, delivering solutions platforms for partners who serve enterprises, creating personal solutions (now called Work Essentials) for people who use Microsoft Office and other Information Worker products, managing standards for Microsoft' s intranet and other methods of internal connection and information exchange, publishing the primary Microsoft intranet portal, and running the company's electronic and physical libraries. His division also sought to understand and promote productive corporate cultures, and to articulate Microsoft's long-term vision of the future of information work. In this capacity, he oversaw the company's Center for Information Work.
In 2005, Rinearson's full-time attention returned to Alki Software Corporation.