He graduated in 2001 ranked first in his class with a Juris Doctor with highest honors.

After his stint at Covington & Burling, he served in the United States Department of Justice Office of Legal Counsel as an attorney-advisor.

Before becoming a judge, he was a partner at Haynes and Boone, where he founded the False Claims Act practice group and worked on healthcare litigation.

[3] On January 23, 2018, President Donald Trump nominated Kernodle to the seat on the United States District Court for the Eastern District of Texas vacated by Judge Michael H. Schneider Sr., who assumed senior status on January 7, 2016.

[8] In December 2020, Texas Republican congressman Louis Gohmert and others filed a suit in Kernodle's court, naming vice president Mike Pence as a defendant in arguing he constitutionally has "sole discretion in determining which electoral votes to count for a given State, and must ignore and may not rely on any provisions of the Electoral Count Act that would limit his exclusive authority.