UFC co-owner Lorenzo Fertitta called the agreement "a seminal moment for this company and for this sport, taking it to another level."
The deal will change the way UFC fighters look.
Instead of a mishmash of sponsors on shorts (or tops for women), they will wear gear with the Reebok logo with perhaps one title sponsor.
"Think more along the lines of European soccer," Fertitta said in a conference call prior to Tuesday's announcement in New York.
Any title sponsor on the Reebok gear will be "a major global brand," promised Fertitta.
"Just that alone is going to completely change the perception of the sport, the perception of the athletes, the level that where we're at," he added. "This is a true game-changer."
The new "athlete outfitting policy" will start in July 2015.
Fertitta declined to detail the value of the Reebok deal but said "the vast majority if not all of the revenues" will go to the fighters in the beginning. The UFC hopes to dip into the revenue itself down the line as it grows.
For the UFC, a partnership with Reebok adds legitimacy to combat sports. Indeed, it's a far cry from condom and gun shop ads that used to adorn fighter shorts.
Fighters will be paid to wear the new gear on a per-fight basis. How much they get will be based on their ranking the day of the weigh-in. Champions will make the most, with subsequent tiers for fighters ranked No. 1-5, 6-10, 11-15 and those not ranked.
The rankings are voted on by a media panel.
Fighters will also get royalties on gear with their likeness.
Previously fighters were essentially allowed to walk in wearing gear advertising their own sponsors. If their sponsor was not connected to the UFC and was of a certain size, it would have to pay the UFC an "affiliation fee."
Some elite fighters also shared in revenue from top UFC sponsors who elected to use them.
Fighters also had their own deals.
Light-heavyweight champion Jon (Bones) Jones, for example, has a deal with Nike. Former welterweight title-holder Georges St-Pierre had his own line with Affliction.
Fighters can keep those sponsors although they won't be able to wear them into the Octagon.
"So no different than any other professional sports league," said Fertitta. "Obviously if you play in the NFL, Tom Brady wears a Nike uniform, DeMarco Murray wears a Nike uniform but Tom Brady is actually sponsored by Under Armour and DeMarco Murray is sponsored by Adidas."
The UFC has some 500 male and female fighters under contract.
"Most of the people I've talked to, they really get it. They're excited about it," said UFC president Dana White.
Now they will have to wear Reebok into the cage and the sponsor banners that were displayed during pre-bout introductions will disappear. But Fertitta says fighters will still have their own look under the new deal.
"It will allow for each of the fighter's individuality but also will provide a unique iconic and consistent look for all the athletes," Fertitta said.
Fighters' cornermen will also wear Reebok gear.
"Interested to see what girls will have for @Reebok apparel. Hoping we have an option to wear more than sports bra and short shorts #modesty," tweeted Victoria bantamweight Sarah Kaufman, ranked No. 5 among 135-pound contenders.
The new partnership will see UFC-Reebok gear in 1,500 Reebok stores and other retail outlets worldwide.
"It'a a massive, massive move for the sport of MMA and the brand of UFC and the fighters' brands," said Fertitta.
Reebok will also invest in research and development "to create and innovate new products for training in the sports of mixed martial arts."
A percentage of revenue from the deal will go to Fight for Peace, a non-profit organization.
The UFC had hoped to announce the Reebok partnership at a Las Vegas news conference last month but did not get it done it in time.
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