Mario Williams attended Richlands High School in Richlands, North Carolina. He recorded over 100 tackles from his defensive end position as a junior. As a senior, Williams played defensive end and running back due to injuries. He averaged over 10 yards per carry as a running back with 590 yards and 3 touchdowns on 58 attempts. On defense he totaled 87 tackles, 13 sacks and forced 5 fumbles. He also blocked 5 field goal attempts on special teams. He earned all-state honors for his performance and was selected to play in the North Carolina Shrine Bowl where he totaled 4 sacks. He was considered to be one of the top 5 defensive end prospects in the nation. He was recruited by Ohio State, Clemson, and Tennessee but opted to accept a scholarship to N.C. State. Mario graduated high school in December and joined the Wolfpack at the Gator Bowl. He was named most dependable defensive lineman in the spring of 2003 and earned a starting spot at defensive end as a true freshman. He finished the season with 56 tackles, 5 sacks and 2 forced fumbles on the year. Mario was named freshman All-American for his performance that season. In the spring of 2004 Williams received the most dependable defensive lineman award, defensive leadership award, and was named most dominant player on the defense. He was the team strength and conditioning champion prior to his sophomore season. He totaled 57 tackles and 6 sacks on the year and was named first team all-ACC at the conclusion of the season. He received the Bob Warren award for integrity and sportsmanship. In the spring of 2005 Williams was named most dependable defensive lineman for the third consecutive year and most dominant defender for the second consecutive year. He had his best year as a junior with 62 tackles and 14 ½ sacks. He was named all-American for his performance as a junior.

Mario Williams has an excellent combination of size, strength, and athleticism for a defensive end. His height and long arms allow him to knock down passes at the line of scrimmage and force turnovers. He has the speed to get around most offensive tackles as well as the size and strength to bull rush them. His size also allows him to be effective against the run. He is very strong at the point of attack although he does have a tendency to play too high at times which causes him to lose leverage. As a pass rusher, he has a good spin move and very good closing speed getting to the quarterback. He relies on his athleticism too much at times and can improve his technique. Mario has proven to be a very durable player and is a hard worker both on the field and in the weight room. He is still developing and improving every year and he will only get better in the future. Mario Williams has a great deal of upside and should be a high first round pick on draft day.