Obama had asked his followers on Twitter to read his memoir to get an insight on events.
Around 887,000 units were sold in the US and Canada, which includes pre-order sales and first-day sales, CNN reported citing Penguin Random House. The publisher said this sale represented "the largest first-day sales total for any book ever published" by the company.
Another publisher said Obama's new book will be a book of "rare consequence" and will do good business, at par with the likes of the Harry Potter series.
"This will be a book of rare consequence. That it will sell as no other book has done since July 21, 2007 -- when Harry Potter and the Deathly Hallows came out, is immensely cheering to booksellers," said Barnes & Noble CEO James Daunt, CNN quoted.
Prior to the opening day, Obama had asked his followers on Twitter to read his memoir to get an insight on events and people that shaped him during his early years.
"My memoir, A Promised Land, is out today. I hope you'll read it. My goal was to give you some insight into the events and people that shaped me during the early years of my presidency. Most of all, I hope it inspires you to see yourself playing a role in shaping a better world," Obama tweeted on Tuesday.