The set, bolstered by its lead pop hit "Suit& Tie" featuring Jay-Z, debuted at No. 1 on the Billboard chart and sold 968,000 units since it was released March 19.
The sales sum also gives Timberlake the best opening sales week of his career, beating his 2006 Grammy-winning album "FutureSex/LoveSounds."
The honors are well-deserved as the 31-year-old was strategic about promoting his comeback effort: He performed at the Grammy Awards, hosted and hit the stage at "Saturday Night Live" and spent an entire week on "Late Night with Jimmy Fallon."
"We're getting a lot of phone calls now to do themed-weeks for people," said Fallon, who added that the show's writers and producers developed a load of material for "Timberweek."
The singer also partnered with Target for the album's deluxe edition and "20/20" streamed on iTunes a week before it was released.
According to Nielsen, Timberlake's disc is the 19th album in the system's history to sell more than 900,000 albums in its debut week.
Of the 19 albums, Timberlake now holds three spots. The Tennessee native previously earned two slots during his younger band boy days with 'N Sync. The pop group's 2000 album "No Strings Attached" and 2001's "Celebrity," sold 2.4 million and 1.9 million in their first week, respectively.
The excitement over the new album has also boosted the American singer-songwriter and actor's older albums including those from N'SYNC.
The achievement also honors the former Mouseketeer as the sixth artist in Billboard history to earn multiple No. 1 albums with both a group and as a soloist.
He joins the elite club in the likes of Eminem, Beyonce, Destiny's Child, and The Beatles, as well as solo efforts from Paul McCartney and John Lennon.
Label industry experts predicted the pop star would sell just 500,000 to 600,000 copies.
A follow up to '20/20' is expected later this year.
The Associated Press contributed to this report.