Kathryn Tappen was born on April 9, 1981, in Morristown, New Jersey. Growing up,  she was a stand-out athlete competing in field and track both in high school and college. She began her broadcasting career at College Sports Television in 2003. She then spent a year and a half at NBC affiliate WJAR in Providence as weekend anchor and weekday sports reporter.

Tappen joined NESN in 2006 as lead studio host for Boston Bruins coverage, also reporting on the Patriots, Red Sox, and Celtics. In 2011, she joined NHL Network as host of NHL Tonight before signing with NBC Sports in July 2014. There, she became the primary host of NHL Live and sideline reporter for Notre Dame Football. Additionally, she completed several Olympic assignments across Sochi, Rio, PyeongChang, Tokyo, and Beijing.

In 2023, Tappen became sideline reporter for NBC’s Big Ten Saturday Night primetime college football games, continuing through the 2025 season. She simultaneously added reporter duties for NHL on TNT and, in March 2024, rejoined NHL Network as studio host and reporter. At the 2024 Paris Games — her sixth Olympic assignment — she was part of the NBCUniversal team that won a Sports Emmy for its coverage.