Warren Earp was born in Pella, Iowa. Little is known about his early life. Like Wyatt and Morgan, he was too young to take part in the American Civil War, as his older brothers James, Newton and Virgil did. He joined his brothers in Tombstone, Arizona in 1880, and worked as a deputy for Virgil during the months that followed. His older brothers had already established a profitable gambling business, and were well established in the law enforcement duties of Tombstone by that time. He did not take part in the Gunfight at the OK Corral (Lake's biography of Wyatt Earp states that Warren was in Colton, California visiting his parents at the time). However, following the March 18, 1882 murder of his older brother Morgan, and the earlier assassination attempt on Virgil, Warren joined Wyatt Earp, Doc Holliday and their comrades in the now famous Earp Vendetta Ride, and was involved in the March 20 1882 killing of Frank Stilwell, for which he was indicted but never convicted.
On July 6, 1900, he became involved in an argument with Hooker's range boss, Johnnie Boyett, inside Brown's Saloon in Willcox. Boyett and Warren had been involved in verbal disputes prior to that night, and rumor was that the two disliked one another due to their mutual affections for the same woman, possibly a local prostitute.
Late that night, the two men, both drunk, began arguing. Warren Earp is alleged to have said "Boyett, get your gun and we'll settle this right here. I've got mine, go and get yours". Boyett left the bar, returning shortly thereafter with two .45 caliber Colt handguns. Boyett called out for Earp, who walked in from another doorway. Immediately upon seeing Earp, Boyett fired two rounds, but missed with both.
Earp stepped calmly outside of the saloon onto the street without ever producing a weapon, just as Boyett fired two more rounds, missing again with both. It is alleged that Earp, possibly hoping to avoid a further confrontation, removed his weapons while outside. Earp then entered again. As Earp walked in, he stated as he opened his coat and vest "I have not got arm. You have a good deal the best of this". Earp continued walking toward Boyett, talking the entire time. As Boyett warned him several times to halt, Boyett appearing slightly frightened but angry. When Earp did not stop, Boyett fired a fifth round, this time striking Earp in the chest, killing him almost instantly. Boyett claimed that he feared for his life, and that by allowing Warren Earp to get too close, he believed his life would be in danger. Warren Earp was found to have in fact been unarmed with pistol, but did have an open pocket knife in his fist. No arrest was made.
Virgil Earp came to Willcox following the murder, under an assumed name. He did his own independent investigation, determining that even if Warren had been intoxicated and talking too much, he had still been murdered. Boyett was not arrested at any stage for the shooting, and sought the protection of the local sheriff, fearing retribution from the Earp brothers. He returned to work on Hooker's ranch, staying out of Willcox for a long period of time. Wyatt did not get involved in the incident, nor did James or Newton. It was later reported, falsely, that the Earps avenged Warren's death by killing Boyett. However, they did not, and he eventually retired from his work as a ranch hand, moving to Redlands, California. He later died in Texas.
Warren Earp was buried in Willcox, at the Pioneer Cemetery.