Lon Oden married for the first time in 1889, but the marriage ended shortly thereafter in divorce, and on March 1, 1891, he joined the Texas Rangers. For a time he worked the region surrounding San Antonio, Texas, but then was sent west to serve with Ranger John R. Hughes. Oden and Hughes were dispatched to Shafter, Texas, due to the Carrasco brothers gang, led by Antonio Carrasco, committing armed robberies in order to steal silver being shipped from the silver mines. Assisted by Ranger and undercover agent Ernest St. Leon, the Rangers set up surveillance on a mine where the thieves were expected to strike, based on inside information gained by St. Leon. When the outlaws opened fire after ignoring the command to surrender, the Rangers killed all three men.
Oden then was sent to El Paso, Texas, where he worked for some time, and where he became acquainted with, and friends with Ranger Bass Outlaw. In 1893, when Ranger Captain Frank Jones was ambushed and killed, John Hughes took over as Ranger Captain for that area. Because Jones and his small band of Rangers were mistakenly inside Mexico when the ambush had taken place, there was to be no prosecution of those responsible. However, still working undercover, Ernest St. Leon supplied a list of names of those known to have taken part in the killing to Captain Jones. Accompanied by a company of Rangers, including Oden and led by Hughes, the Rangers tracked down and killed all 18 men on the list, either by shooting them or by hanging them.
Oden had by this time settled in Ysleta, Texas. During this time he took part in several Ranger raids, and over time he and his fellow Rangers working that area drastically reduced the number of robberies and cattle rustling in that region. On April 5, 1894, Bass Outlaw was shot and killed by John Selman in El Paso. Outlaw was not innocent in his own death, a fact which made it all the more difficult to accept for Oden. Outlaw, intoxicated and furious at what he deemed mistreatment by a local judge, had shot and killed Ranger Joe McKidrict inside a brothel. When confronted by Selman, a constable at the time, Outlaw and Selman became involved in a gunfight, leaving Selman wounded, and Outlaw dead. Two years later, on April 5, 1896, lawman and friend to Outlaw, George Scarborough, would shoot and kill Selman in a gunfight over Selman having killed Outlaw.
Lon Oden continued working as a Ranger, and by this time he had developed a considerable reputation due to the numerous and mostly unknown outlaws and cattle rustlers he had either killed in shootouts, arrested, or hanged. He had become involved with widow Annie Laura Hay around 1894. On January 17, 1997, the couple married, and he left the Rangers shortly thereafter to become a rancher and businessman. He started a successful ranch in Marfa, Texas. He died there of an unknown lung ailment on August 11, 1910. In 1936, his daughter Annie Laura Oden Jenson published his diary of his exploits as a Ranger.