Kuechly is of German American descent. He was born in Cincinnati, Ohio and grew up in Evendale, Ohio. He attended St. Xavier High School in the Finneytown area of Cincinnati, where he played linebacker and safety for head coach Steve Specht. As a junior in 2007 he had 147 tackles, six sacks, two forced fumbles, three fumble recoveries, two interceptions, and a touchdown as a linebacker. He helped his team go 15-0, winning the Division 1 Ohio state title, and finishing at the top of several national polls (Calpreps.com and Prepnation.com) as the best high school team in America. As a senior in 2008 he had 130 tackles, a sack, three forced fumbles, two fumble recoveries and an interception. Kuechly was a two-time All Greater Catholic League selection at St. Xavier, gaining first-team honors in 2008.
Regarded as a three-star recruit, Kuechly was listed as the No. 44 outside linebacker prospect in the class of 2009, which was headed by Jelani Jenkins and Nico Johnson. After official visits to Boston College, Virginia, Duke, and Stanford, Kuechly committed to the Eagles in January 2009.
As a true freshman in 2009, Kuechly became the Eagles' starting outside linebacker after Mark Herzlich announced that he would miss the season after being diagnosed with Ewing's sarcoma, a rare form of cancer. He finished the season with 158 tackles (87 solo), which led the team and conference, as well as being second nationally (first among freshmen). He was the first true freshman in team history to lead the team in tackles and almost broke the freshman tackle record set by Stephen Boyd in 1991. He also had a sack and returned an interception for a touchdown. For his play he was named the 2009 ACC Defensive Rookie of the Year and was on the 2009 CFN All-Freshman Defensive Team.CFN went even further and named the true freshman Kuechly to its All-America team. In the Emerald Bowl, Kuechly was named the defensive MVP, registering 16 tackles in a losing effort.
He moved to middle linebacker at the beginning of his sophomore season. He went on to lead the country with 183 tackles (110 solo) and had an ongoing streak of 21 straight games with at least 10 tackles at the end of the season. Kuechly was named a finalist for the Butkus Award and the Nagurski Award. He broke BC's single season record for tackles, topping the previous record of 165, held since 1991 by Tom McManus. After the season, Kuechly was named a unanimous first-team All-American. He was the first consensus All-American for the Eagles since Jamie Silva in 2007. Boston College played in the Kraft Fight Hunger Bowl (the same bowl as the Emerald Bowl from the previous season with a change of corporate sponsorship) at the end of the season and Kuechly was named the defensive MVP for a second time.
Kuechly led the nation with 191 tackles (102 solo) during the season, averaging nearly 16 tackles per game. Kuechly compiled his stats in the 12-game regular season, as the team finished with a 4-8 record and was ineligible for post-season play. He still almost broke the NCAA Football Bowl Subdivision (FBS) single-season tackle record (193, set by Lawrence Flugence in a 14-game season) and did break the single season tackles-per-game record with 15.9 (previously held by Rick Sherrod with a 15.6 average over a 10-game season). He broke the team and conference single-season tackle records, records that he had set the year before.
In only three seasons of play, Kuechly set the BC and ACC career tackle records with 532 tackles, eclipsing the previous record of 524 held by Stephen Boyd and only 13 short of the NCAA FBS record held by Tim McGarigle. On December 4, Dick Butkus personally presented the 2011 Butkus Award to Kuechly at the Boston College team banquet a week before the expected formal announcement of the recipient. Kuechly went on to win the Lombardi Award, the Lott IMPACT Trophy, and the Bronko Nagurski Trophy, and was recognized as a consensus first-team All-American for the second consecutive year.
"I call him Clark Kent, and he can turn into Superman on Saturdays and Sundays. He's one of the cleanest players in this draft. His instincts and his pass-coverage ability might be the best of any linebacker I've seen come out of the draft."
On January 6, 2012, Kuechly announced his intention to forgo his final year of college eligibility and enter the 2012 NFL Draft. At the time of his announcement he was rated the top linebacker available in this draft: Mel Kiper ranked him tenth on his "Big Board", while Todd McShay ranked him thirteenth in his "Top 32". Kuechly quashed any lingering doubts about his athleticism with his performance at the combine, demonstrating rare pass coverage abilities which would allow him to be a "three-down" inside linebacker (i.e. not subbed-out on obvious passing downs) which raised his draft stock even further. Kuechly also had the highest score on the Wonderlic Intelligence test among linebackers with 34.
He was drafted by the Carolina Panthers in the first round: the first linebacker selected and the 9th overall pick. On May 10, 2012, Kuechly signed a 4-year, $12.58 million contract.
"I love that when that passion comes out of him, maybe a sprawl or a flex or something like that. But then, off the field? Completely unassuming, we'd walk right by him, and you wouldn't even know he was an NFL player... kind of has that Clark Kent air about him. That's why I call him 'Super Luke'."
Kuechly began the season at outside linebacker instead of middle linebacker; Coach Ron Rivera decided to start veteran Jon Beason at middle linebacker due to his experience, but had considered starting Kuechly at middle linebacker and shifting Beason to the outside. When Beason was placed on injured reserve due to a torn Achilles tendon, Kuechly was moved to middle linebacker. Due to his strong performance at middle linebacker, Rivera announced that Kuechly would be the team's long-term starter at that position even after Beason returns from his injury for the 2013 season. In a 30-20 victory over the Atlanta Falcons in Week 14, Kuechly recorded a career-high 16 tackles and was honored as NFC Defensive Rookie of the Week; Kuechly received the NFC Defensive Rookie of the Month award in December, recording a league-high 59 tackles over the final five games of the season. He became the second Panther after Julius Peppers to receive the award. Kuechly led the league with 164 tackles during the regular season and recorded 8 pass deflections, 1 sack, 2 interceptions, and three fumble recoveries. He was awarded the AP Defensive Rookie of the Year and received the Defensive Rookie of the Year award from Pro Football Weekly.
While not being an official stat kept by the NFL, after tape review, Panthers coaches credited Kuechly with a franchise record 205 tackles, surpassing James Anderson’s 174 set in 2011, and became the first rookie to lead the NFL in that department since Patrick Willis in 2007. Kuechly was rated as the 79th best player on the NFL Top 100 list.
During the season opener against the Tampa Bay Buccaneers, Kuechly recorded 9 tackles, a sack, a forced fumble, and had a tipped pass that led to an interception.  In a week 2 game against the Detroit Lions, Kuechly recorded 11 tackles and 2 pass deflections en route to a 24-7 victory. During the Panthers week 5 victory over the Chicago Bears, Kuechly was credited with 15 tackles without a missed tackle and allowed only 47 yards on nine receptions in coverage. Through the first five games of the season, Pro Football Focus has rated Kuechly as the best inside linebacker in the NFL. During Week 7 against the Green Bay Packers on October 19, 2014, Kuechly was ejected for making inadvertent contact with an official; while trying to break free of a pile, Kuechly was grabbed from behind by an official. Not knowing it was an official, Kuechly swung his arm, resulting in his ejection. The NFL later determined that Kuechly should not have been ejected.
^The name Küchli(n)/Kuechly (German pronunciation: [ˈkʏçlɪ]) is a variation of the Upper German surname Kuchler/Küchler, an occupational name for a pastry cook, derived from Küchle, a southern diminutive of Kuchen (“cake”). See Hanks, Patrick, ed. (2003). Dictionary of American Family Names. New York: Oxford University Press. p. 361. ISBN0-19-516558-6.