Kornacki is the multimedia anchor and data analyst for much of MSNBC's The Place for Politics campaign coverage, which airs during Election Day in the United States since 2016.

[8][9] He started his journalism career as a reporter for PoliticsNJ.com,[10] a New Jersey political news site owned by David Wildstein, where he worked from 2002 to 2006.

[12] From 2012 to 2013, Kornacki co-hosted The Cycle on MSNBC with political strategist Krystal Ball, pop-culture commentator Touré Neblett, and conservative columnist S.E.

On May 8, 2017, Kornacki was named National Political Correspondent for NBC News Group, with plans to continue co-hosting the 4 p.m. edition of MSNBC Live with Nicolle Wallace.

[23][24][25] He was also approached to bring his unique analytic style to the sports division of NBCUniversal, first appearing on Football Night in America in December 2020 to break down playoff scenarios for the remainder of the 2020 NFL season.