He attended San Marcos High School in Santa Barbara, where he was named the Channel League's Co-Most Valuable Player on defense and earned a first-team all-league selection.

Mack compiled a 3.61 undergraduate GPA at the University of California, Berkeley as a legal studies major.

[8] He also won the Morris Trophy in 2007 and 2008, making him the third offensive lineman and the first since Washington's Lincoln Kennedy in 1991 and 1992 to win the award twice.

Projected as a first-to-second rounder by Sports Illustrated, Mack was the highest ranked center available in the 2009 NFL draft.

On December 27, 2013, Alex Mack was voted to his first Pro Bowl Selection, after having been added in 2011 to replace an injured player.

[19] On April 9, 2014, it was announced that the Jacksonville Jaguars had offered Mack a five-year contract, worth reportedly $42 million.

During Week 6 against the Pittsburgh Steelers on October 12, 2014, Mack was carted off the field due to a leg injury.

X-rays tested positive that his leg had a broken fibula, forcing Mack out for the rest of the 2014 campaign.

[24][25] In the 2016 season, Mack and the Falcons reached Super Bowl LI, where they faced the New England Patriots.