The Waterloo, Ont.-based company said an "established partner" made the purchase, though a spokeswoman for the company said confidentiality reasons prevent it from revealing the identity.
The former Research In Motion said shipments of the phones will start immediately.
"An order for one million devices is a tremendous vote of confidence in BlackBerry 10," said Rick Costanzo, executive vice president of global sales at BlackBerry.
It's the first time the smartphone maker has revealed sales data for its new devices.
Chief executive Thorsten Heins has said the new BlackBerry Z10 touchscreen phone is selling better than the company expected, while Canadian carrier Bell (TSX:BCE) said last month that pre-orders broke its previous records for BlackBerry.
The phone hit stores in Canada and the United Kingdom in February, with several other international markets following soon after.
Meanwhile, the U.S. rollout of the device continues as another carrier announced when it would carry the new touchscreen devices. Verizon Wireless says it will begin stocking the BlackBerry Z10 on March 28, with pre-orders starting on Thursday.
Earlier this week AT&T announced it would begin to offer the phone on March 22, while T-Mobile expects to carry the BlackBerry device for its business customers as early as the end of this week, though it did not provide details on the availability for non-business customers.
A keypad version of the phone, dubbed the BlackBerry Q10, is expected this spring though an official date hasn't been announced.
BlackBerry will report its fourth-quarter earnings on March 28.
Shares in the company closed up $1.21 at $16.04 on the Toronto Stock Exchange.