Conner made his official WWF debut in 1997 as a member of Faarooq's Nation of Domination heel stable, most notably along with Rocky Maivia, Kama Mustafa, and Mark Henry. In early 1998, the group turned on Faarooq, allowing Maivia to assume leadership, now going by the name "The Rock". Kama also changed his name to "The Godfather" and began portraying a pimp character. D'Lo and Henry eventually turned on both Rock and Godfather separately, moving into a feud with the Rock before finally branching out as a moderately successful tag team, later turning face along the way. Prior to the face turn, Brown had started wrestling with a chest protector, supposedly for a torn pectoral muscle sustained in a against Dan "The Beast" Severn. Instead, he used the chest protector to his advantage, making his finishing move, the Lo Down, more effective. His career peaked when he held the European and Intercontinental Championships simultaneously. This feat was only duplicated by Jeff Jarrett, Kurt Angle, and Rob Van Dam, all of whom became World Heavyweight Champions in some form since said double reigns.
Brown was involved in inadvertently ending the career of Darren Drozdov on October 5, 1999 when a running powerbomb was botched due to Droz's baggy shirt. The match was to be aired on the October 7 edition of SmackDown!. The match was never aired and Drozdov suffered a severe neck injury, leaving him a quadriplegic. During the rest of the year and into some of the next, Brown became an ally of former fellow Nation member The Godfather, emulating his dress and walking motions. The teaming ended when Brown turned heel on the Godfather.
Brown then formed a tag team in July 2000 with Chaz named Lo Down. The team mostly wrestled on Sunday Night Heat and WWE Jakked / Metal. Shortly after the team formed, Tiger Ali Singh joined the team to become their manager. The tag team then came dressed towards the ring in Arabic ring attire and took on a gimmick very similar to Tiger's. The team was removed from WWF TV in January 2001. Chaz and Singh were later be released by WWE while D'Lo Brown stayed in WWE's developmental territory. D'Lo returned to TV on the April 28, 2002 episode of Heat, losing to Eddie Guerrero.
For the rest of the year, Brown mostly wrestled on Heat, did a little bit of commentary on the show, and even started a brief feud with Raven. In late 2002, Theodore Long retired as a WWE referee and managed D'Lo, who had complained about acts of racism being talked about on him during his matches. D'Lo started Theodore Long's group Thuggin' and Buggin' Enterprises which eventually turned into a group of African Americans who worked an angle in which they felt they were victims of racism and were being held down by the "white man." With Long's managerial services, D'Lo Brown went undefeated for several weeks.
Brown faced Booker T in a losing effort on the February 10, 2003 episode of Raw. His involvement with Thuggin' and Buggin' Enterprises was brought to a close when footage was shown on the February 16 episode of Heat of Theodore Long kicking D'Lo Brown to the curb and introducing his replacement Rodney Mack. He was then released from his WWE contract on February 14, 2003.
In 2008, Brown wrestled in a number of dark matches for World Wrestling Entertainment, with his most notable win against Ron Killings.
Months later, on June 5, 2008, WWE announced that Brown had been signed to a contract, and he began working more dark matches for the company. He made his television return on the July 21, 2008 edition of Raw, to defeat Santino Marella and he faced him two more times, one a tag team where he teamed up with Kelly Kelly to face Santino Marella and Beth Phoenix. In the second match Beth got Brown DQ'ed for standing in front of Santino when D'lo was about to jump on him. Despite this win, Brown lost to Marella on Raw and has mainly been competing in dark matches before the flagship broadcast. Brown returned to Raw to face Mike Knox. He lost after Mike Knox delivered a Knox Out. On January 9, 2009, it was announced on WWE.com that Brown had been released from his World Wrestling Entertainment contract.