Severn made his first appearance in the WWF on June 23, 1997, to join the color commentary team. Severn had not signed a contract with WWF by this point. He commentated on Ken Shamrock's match against Rockabilly. Ken won the match with a belly-to-belly suplex. After the match, the two had a stare down and eventually shook hands.
Severn debuted in the World Wrestling Federation in 1998. Severn was first seen attacking The Headbangers when they were feuding with Bob Holly and Bart Gunn. In his debut match, he defeated Flash Funk in quick fashion. He was briefly managed by Jim Cornette, who commentated during his matches. Like Flash Funk, he defeated multiple opponents afterwards, the likes of Savio Vega and Mosh, in quick fashion and by showing some of his mixed martial style and ability. This led to a winning streak.
He then feuded with Ken Shamrock. During his one-year tenure, he competed in the Brawl for All tournament, beating The Godfather in the first round. However, he opted out prior to the quarterfinals, allowing The Godfather to advance by default. He would also take part in the 1998 King of the Ring tournament, defeating D'Lo Brown and Owen Hart before losing to The Rock in the semi-finals.
Dan made his WWF Shotgun Saturday Night debut in the opening match against G.I Will in a squash match. On the June 8, 1998, episode of Monday Night Raw, Severn would injure D'Lo Brown's rib cage via the bow and arrow submission hold, causing him to wear a chest protector for the next few months. On July 28, 1998, Severn competed against D'Lo Brown for the WWF European Championship. He would win the match by disqualification, meaning Brown retained the championship.
Later that year he was involved in a storyline with Owen Hart, where Hart caused an injury to the neck of Severn, via a piledriver. He was part of the 1999 Royal Rumble, being the eighth entrant and lasting almost six minutes before being eliminated by Mabel. He left the WWF soon thereafter. His last match was on the following Raw, where Steve Blackman defeated Severn via disqualification. In house shows leading up to this, Blackman would defeat Severn every time.