Hightower was born in Lewisburg, Tennessee. He attended Marshall County High School in Lewisburg, where he played for the Marshall County Tigers high school football team. He first drew recognition his sophomore year when the team's starting running back quit the team. In the last four games of the season, he rushed for over 1,000 yards and seven touchdowns. After growing to 6 ft 2 in (1.88 m) prior to his junior year, Hightower was moved to linebacker and tight end. He collected 98 tackles, two sacks, and seven forced fumbles, while at TE, he caught 18 passes for 253 yards and four touchdowns.
Having grown to six feet, three inches tall as a senior, Hightower again switched positions, playing defensive end. After recording 168 tackles (14 for loss), five forced fumbles, five interceptions and four fumble recoveries, he was named 3A Mr. Football Lineman of the Year and The Tennesseans Defensive Most Valuable Player in 2007. He also added 875 yards and 19 touchdowns on offense.
Hightower was selected to play in the U.S. Army East West All-Star Game in San Antonio, Texas.
Hightower attended the University of Alabama, where he played for coach Nick Saban's Alabama Crimson Tide football team from 2008 to 2011. As one of only two true freshmen to be regular starter for the Crimson Tide in 2008, Hightower started 12 games while playing in all 14 at weakside inside linebacker ("Will") in the Alabama's 3–4 defense, next to Rolando McClain who occupied the other inside linebacker spot ("Mike"). Hightower recorded 64 tackles (4th on the team) and 2.5 tackles for loss, while also having one forced fumble and two fumble recoveries. He had at least one tackle in each game and had five or more stops in seven of 14 games, including 10 against Tulane and a career-high 11 at LSU. He was subsequently named to numerous Freshman All-American teams.
For the 2009 season, during the Arkansas game, Hightower suffered a knee injury in the first quarter when he was cut blocked by an Arkansas lineman. He was diagnosed a torn anterior cruciate ligament in his left knee and missed the rest of the season with surgery.True freshmanNico Johnson replaced him at weakside linebacker. Hightower recorded 16 tackles including 4 tackles for loss. Having played only four games, he was granted a medical redshirt making him a redshirt sophomore in 2010.
Returning for the 2010 season, Hightower was expected to "be the nucleus of a young defense". He replaced McClain as Alabama’s middle linebacker, and captained a defense that ranked No. 1 nationally in all five major categories—scoring defense (8.8 ppg), total defense (191.3 ypg), rushing defense (74.9 ypg), pass efficiency defense (83.9 ypg) and pass defense (116.3 ypg). Hightower led the team with a career-best 81 tackles, including 37 solo stops, as well as three sacks (−16 yards) and 9.5 tackles for loss (−35 yards). He also registered eight quarterback hurries, one interception, one blocked field goal and three pass breakups.
As early as April 2011, Hightower was projected a potential first-round draft pick in the 2012 NFL Draft. Shortly after the 2012 BCS National Championship Game, he announced his decision to forgo his final year of eligibility. Right after the season ended, he was projected a late first-round selection. After solid performances at the NFL Combine and Alabama Pro Day, he was still regarded as a late first-rounder. On April 26, 2012, Hightower was selected by the New England Patriots with the 25th overall pick in the draft.
On July 19, 2012, Hightower agreed to a contract with the Patriots. It was reported that the deal was four years, worth $7.7 million. In his first game for the Patriots, he recovered a fumble (forced by fellow debuting rookie Chandler Jones) and returned it for a touchdown. 2013 proved to be a successful season for Dont'a; he led the team with 97 combined tackles. In Super Bowl XLIX Hightower stopped Seattle Seahawks running back Marshawn Lynch at the 1-yard line, preventing Seattle from going ahead. On the next play Malcolm Butler intercepted Russell Wilson, clinching the game and a fourth Super Bowl championship for the Patriots.
On April 30, 2015, the Patriots picked up the fifth-year, $7.751 million option of Hightower's contract. Through the season's first 11 games, over which the Patriots went 10-1, Hightower racked up 55 tackles and 3.5 sacks. He left the Nov. 29 game against the Denver Broncos, won by the Broncos, 30-24, with what was reported to be a sprained MCL in his left knee.