On June 13, 2016, Gurv and Harv Sihra were announced as participants in WWE's Cruiserweight Classic tournament. On June 23, both Sihras were eliminated from the tournament in their first round matches, with Gurv losing to Noam Dar and Harv losing to Drew Gulak. The Bollywood Boyz debuted in the WWE developmental territory NXT at the September 15 tapings. They also took part in the second annual Dusty Rhodes Tag Team Classic; however, they were eliminated by The Authors of Pain in the first round. On the premiere episode of 205 Live in November 2016, The Bollywood Boyz defeated Tony Nese and Drew Gulak in their debut tag team match.
On the April 18, 2017 episode of SmackDown Live, they made their main roster debut as The Singh Brothers; Gurv was renamed Sunil Singh, while Harv was renamed Samir Singh. They interfered in a six-pack challenge match to determine the number one contender for Randy Orton's WWE Championship at Backlash, helping Jinder Mahal win the match, turning heel in the process. They also interfered in Orton's House of Horrors match against Bray Wyatt at Payback, distracting Orton long enough for Mahal to attack him with the stolen WWE Championship, allowing Wyatt to take advantage and defeat Orton with a Sister Abigail. At Backlash, the Singh Brothers were at ringside for Mahal, ultimately helping him defeat Randy Orton and capturing his first WWE Championship. At Money in the Bank, the two interfered in Mahal's WWE Championship rematch against Orton, ultimately helping him retain the title. At Battleground, they interfered in Mahal's Punjabi Prison match against Orton for the WWE Championship, being fought off by Orton. However, The Great Khali interfered, allowing Mahal to retain the title. After being injured, the brothers wore a neck brace and a cast, respectively. They soon recovered and continued to distract Mahal's foes in matches, including helping Mahal defeat Shinsuke Nakamura at SummerSlam and Hell in a Cell to retain the title. On the November 7 episode of SmackDown Live, after Mahal lost the title to AJ Styles, they were attacked by Mahal for being unsuccessful in helping him retain the WWE Championship. On the December 12 episode of SmackDown Live, The Singh Brothers showed signs of a face turn after hugging Styles and insulting Mahal, but remained heel after being attacked by Styles. On the January 16, 2018 episode of SmackDown Live, Samir suffered a torn ACL during a ringside brawl with Bobby Roode. On April 8, Sunil made his WrestleMania debut at WrestleMania 34, accompanying Mahal in a fatal four-way match against Bobby Roode, Randy Orton and Rusev for the United States Championship, which Mahal won after Sunil distracted Rusev.
On April 16, The Singh Brothers moved to Raw brand as part of the Superstar Shake-up alongside Jinder Mahal. On the October 15 episode of Raw, Samir returned after his injury to unite with his brother and Mahal. Sunil and Samir wrestled their first match on January 1, 2019 episode of Raw when they teamed up with Mahal to defeat Heath Slater and Rhyno, in a 2-on-3 handicap match.
During the 2019 WWE Superstar Shake-up, the Singh Brothers and Jinder Mahal were drafted back to SmackDown. The following week, the Singhs were drafted over to 205 Live, separating them from Mahal. Following the trade, they changed their gimmicks to being very similar to their previous gimmick of The Bollywood Boyz and began competing in tag team matches regularly.
On October 21, 2019, Sunil (after a distraction from Samir) pinned R-Truth backstage during Raw to win the WWE 24/7 Championship, marking the first title for either of the Singhs in WWE. Ten days later at Crown Jewel, Sunil lost the title to R-Truth after they both were eliminated from a battle royal, but later in the evening Samir pinned Truth backstage to win the title for the first time in his own right. Eighteen days later, Samir lost the title backstage on an episode of Raw to R-Truth, who was disguised as a doctor. Following their 24/7 Championship pursuits, both brothers regained and lost the championship at various house shows. On the October 9, 2020 edition of 205 Live, it was announced that The Singh Brothers would return to the brand, going back to The Bollywood Boyz gimmick. On June 25, 2021, they were released from their WWE contracts.