TiMER director Jac Schaeffer wrote the most recent draft of the script, and Shortland fended off other directors in contention like Amma Asante and Maggie Betts.
Reports suggest Marvel bosses met with over 60 filmmakers over the past 18 months before agreeing to hand the job to Shortland earlier this week.
The Australian director made her name with her incredible 2004 debut Summersault, and her most recent movie - kidnap thriller Berlin Syndrome - was one of our hidden gems of 2017.
Black Widow is a key member of the Avengers and her character is deserving of her own film.
It's a big risk for Marvel, as Australian Shortland only has nine director credits to her name - and only four are full-length features.
While Australian actors have been prominent in Marvel superhero movies, with Hugh Jackman as Wolverine and Chris Hemsworth as Thor, Shortland will be the first Australian director in the studio's so-called Cinematic Universe.
Black Widow does not yet have an official release date.
The Black Widow was first introduced to the MCU in 2010's Iron Man 2 and has since then appeared inThe Avengers, Captain America: Winter Soldier, Avengers: Age of Ultron, Captain America: Civil War, and Avengers: Infinity War.