The RSPB said 2,270 black-tailed godwits spent time on the island this spring, almost double the previous record of 1,320 in 2013.
The majority of the birds this year were found in a tiny field in Kilmoluaig.
Godwits often stop off in the Hebrides to refuel during their migration to Iceland, where they breed.
Spotters identified some of the birds as having come from France, Portugal and Spain due to the rings fitted on their legs.
John Bowler, Tiree officer for RSPB Scotland, said: "Black-tailed godwits are known to stop off here for food on their way to Iceland, particularly when adverse northerly winds hamper their progress across the North Atlantic.
"So, with huge numbers of golden plover already noted on Tiree during pretty windy conditions, it wasn't a huge surprise when black-tailed godwits started turning up, too. However, to see flocks of this size is just incredible.
"Hopefully they will enjoy a good breeding season this year and I'm already looking forward to seeing them pass back through Tiree in the autumn."
A record-breaking number of migrating birds have been recorded on the Hebridean island of Tiree this year.