The soldiers, from 1st The Queen’s Dragoon Guards, were in Nevada for a training exercise when gunman Stephen Paddock opened fire on concertgoers.
At least 59 people died and more than 527 were injured in the atrocity, which is the deadliest mass shooting on US soil.
The Ministry of Defence confirmed three troops provided emergency first aid and medical assistance to victims before ambulances arrived.
A spokesman said: “We can confirm that a number of serving personnel from 1st The Queen’s Dragoon Guards provided assistance to the wounded following the heinous shooting in Las Vegas.
“Our thoughts go out to those affected by this terrible act.”
Speaking of their actions, a military source told the Mirror: “Due to their experience, the guys who heard the noise knew instantly it was gunfire. Their training immediately kicked in and they rushed to the festival to help.
“All soldiers in the cavalry are given medical training designed to preserve life on the battlefield. The injuries they were seeing were the ones they are well versed in treating”.
Paddock, 64, killed 59 people and injured at least 527 more in a terrifying 10 minute-long attack yesterday.
The attack took place during the last night of the Route 91 Harvest country music festival in Las Vegas.
The gunman opened fire from his hotel room on the 32nd floor of the Mandalay Bay Hotel, where he had been holed up since Thursday September 28.
When officers broke into his room, they found that he had taken his own life.
Officers found an arsenal of 23 guns in the hotel room, some of which were fitted with scopes.
Paddock also had two “bump-stocks”, devices legal in the US which effectively turn semi-automatic rifles into automatic machine guns.
Police are not treating the attack as terror-related, despite Nevada law defining terrorism as “any act that involves the use… of violence which is intended to cause great bodily harm or death to the general population”.
The killer was a multi-millionaire real estate investor and former accountant, according to his brother.
He was not known to police, and had no criminal history except a routine traffic violation.
US President Donald Trump tweeted a message of support to those affected.
He wrote: “My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!”
Theresa May took a break from the Conservative Party conference in Manchester to condemn the attack.
She said: ”The UK’s thoughts are with the victims and the emergency services responding to the appalling attack in Las Vegas.”