It is a record for the site which crowdsources cash to fund start-ups.
Eric Migicovsky initially sought $10,000 over a five-week period but the total, six days in, now stands at $3.4m.
It is the fifth Kickstarter project to make more than $1m.
The Pebble watch reached the $1m mark in 28 hours. The firm behind the device, which has been designing smartwatches for three years, said that it was "blown away" by the support.
The watch has an electronic paper screen and connects via Bluetooth with iPhones or Android powered devices to allow users to customise the watch face and download apps."