He played college football at Illinois,[1] and was selected in the sixth round of the 2016 NFL draft by the New England Patriots, with whom he won two Super Bowl championships.

[2] The 6 ft 4 in (1.93 m), 295 pounds (134 kg) Illinois native helped the Fighting Irish to win state championships in the 2008 and 2010 seasons.

[3] Karras graduated in 2011 and received four collegiate football offers including Illinois, Indiana, Iowa State and UCLA.

Karras earned a bachelor's degree in communications in 2014 with a plan to complete a master's program in the fields of recreation, sport and tourism.

[6] He made the Patriots 53-man roster and was the starting right guard in the season opener against the Cardinals due to the injuries of Shaq Mason and Jonathan Cooper.

Karras contributed to the Patriots finishing with a 14–2 record and earning the top-seed for the AFC playoffs.

[7][8] On February 5, 2017, Karras was part of the Patriots team that won Super Bowl LI.

[13] He made his first start of the season in Week 11 at center, filling in for starter David Andrews, who was out with an illness.

[14][15] Karras and the Patriots reached Super Bowl LII, but were defeated by the Philadelphia Eagles by a score of 41–33.

[17] The Patriots reached Super Bowl LIII where they defeated the Los Angeles Rams 13–3.

[19] Karras began the 2019 season as the Patriots' starting center after David Andrews was placed on season-ending injured reserve.