He was selected by the Rams in the third round of the 1998 NFL draft, and played his entire twelve-year professional career with them.
As a sophomore, he started every game at left defensive end and recorded 62 tackles and a career-high eleven sacks.
[6] Little was expected to be a first-round draft choice, but his "in-between" size left teams not sure if he would be a linebacker or a defensive end in the NFL.
He was inactive for four games before being placed on the non-football injury list due to legal issues surrounding his drunk driving crash.
Little added 20 pounds with weight training and extra eating to help him make the switch and in that role Little had 5 sacks and totaled 17 tackles.
On April 24, 2001, Leonard Little agreed to a one-year tender offer of $512,000, the minimum level for a restricted free agent.
Little would enter games in passing situations in place of starting left defensive end Chidi Ahanotu.
Rams defensive line coach Bill Kollar said, "He's become an every-down player, he's doing a good job in the running game, and his pass rush is better.
[13] He recorded 12 sacks (6th most in the NFL) and a franchise-record nine forced fumbles for the season (surpassing Deacon Jones's six in 1968).
[12] He played notably in the season finale against the San Francisco 49ers by recording nine tackles (five solo), one QB pressure, a season-high 2 sacks, and a career-high three forced fumbles.
The following year, he was named an All-Pro and Pro Bowl selection; he had 12.5 sacks, third in the NFC (fourth in the NFL), six forced fumbles and an interception.
Against the Minnesota Vikings on November 30, 2003, Little had eight tackles (six solo), a career-best four sacks, three QB pressures, and two forced fumbles.
He continued his fast start, with four sacks in the first six games [16] but slumped after the death of his brother, Jermaine, who was murdered in Harriman, Tennessee, on October 18, 2005.
[20] Little sprained his big toe when his left foot was caught in the turf in a 22-3 loss at Baltimore on October 14, 2007.
On November 5, 2007, Little was placed on injured reserve, ending his season with only one sack, and had surgery that week to repair the torn ligament in his left big toe.
NFL.com's Greg Cosell described one of Little's plays versus the Jacksonville Jaguars as, "Little 36-yard interception return TD was an unbelievable read by Little.
In the off-season Little, an unrestricted free agent, accepted and then canceled a meeting with the New Orleans Saints to discuss the possibility of signing with the defending Super Bowl champions.
Key After leaving a birthday party in 1998, Little crashed into and killed Susan Gutweiler in St. Louis, Missouri who was on her way to pick up her son from a concert.
When tested, his blood alcohol content was 0.19 percent, 0.11 points exceeding the legal limit of 0.08 in the state of Missouri.
Little pleaded guilty to involuntary manslaughter and received a 90-day sentence of work in a city workhouse, four years probation and was ordered to undergo a thousand hours of community service.