The move reflects the Chicago carrier's aim to support the Biden administration's effort to encourage more people to get their COVID-19 vaccination.
Shares of United Airlines at last check were up 1.1% to $55.90.
Under the terms of the "Your Shot to Fly" sweepstakes, any new or existing MileagePlus member who uploads their vaccination records to the airline's mobile app or website between Monday and June 22 can enter to win a round-trip flight for two, in any class of service, to anywhere in the world United flies.
United said it would give away 30 pairs of tickets throughout June.
In addition, United on July 1 will announce five randomly selected MileagePlus sweepstakes entrants who've won the grand prize: travel for a year for themselves and a companion, in any class of service, anywhere in the world United flies.
"We're proud to do our part to incentivize people to get their shot," United Air Chief Executive Scott Kirby said in a statement. "Thanks to the vaccine, more and more destinations are opening up for travel – and we know our customers are eager to fly."
The Centers for Disease Control has said that vaccinated people don’t have to wear masks or socially distance in most places.
As of early Saturday, 129 million Americans, or 38.9% of the country's population, had been fully vaccinated, according to the CDC's data.
Vaccines have been a source of controversy with many people refusing to get the injections.
Last week, United said it would add more than 400 daily flights to its July schedule and increase services to reopened European destinations amid surging summer travel bookings.
In April, United reported a wider-than-expected first-quarter net loss on a two-thirds drop in revenue.