The star-studded HBO drama already boasts a cast that includes Nicole Kidman, Reese Witherspoon, Shailene Woodley, Laura Dern, Zoë Kravitz, Alexander Skarsgård and Adam Scott.
Kidman and Skarsgård have been sweeping awards season, each earning Golden Globes and SAG Awards for their performances as Celeste and Perry Wright.
Streep will reportedly play Mary Louise Wright, the mother of Skarsgård's character.
Despite the — spoiler alert — death of his abusive character in the Season 1 finale, Skarsgård is also rumoured to be returning for Season 2 in some capacity.
According to The Hollywood Reporter, Streep's character is "a woman who is concerned for the well-being of her grandchildren following her son Perry's death," who comes to Monterey "searching for answers."
Show creator David E. Kelley has apparently already written scripts for the upcoming seven-episode second season. Andrea Arnold will replace Jean-Marc Vallée as the director of all seven upcoming episodes.
HBO says that the new season will delve into the "malignancy of lies, the durability of friendships, the fragility of marriage and, of course, the vicious ferocity of sound parenting."
See some of the reaction to the huge casting news below.
Beyond thrilled to have the one, the only, Meryl Streep joining the cast of #BLL for season 2. Get ready for more wine, secrets, and Big Little Lies. Monterey better watch out!!! pic.twitter.com/VWYcUl7rzd— Reese Witherspoon (@RWitherspoon) January 24, 2018
Some memories are so visceral, you realize as they happen that they'll be with you forever. I'll always remember where I was when I heard about Meryl Streep joining Big Little Lies.— Ben Platt (@BenSPLATT) January 24, 2018
Nicole Kidman and Reese Witherspoon after casting Meryl Streep for Big Little Lies pic.twitter.com/foBfGBIGq4— sanan sarxan (@sanan_sarxan) January 24, 2018
I'm only watching Big Little Lies 2 if Meryl Streep plays all the local eyewitnesses blabbering to the cops in various disguises.— Louis Virtel (@louisvirtel) January 25, 2018
After years away in the Oscar game, I believe it is brave of Meryl Streep to return to TV to win custody of the Emmys. pic.twitter.com/yjHSNq9f03— Louis Virtel (@louisvirtel) January 24, 2018
Meryl Streep is gonna play Nicole Kidman's mother in law in Big Little Lies OHMYGOD pic.twitter.com/uUDsEjS1ct— dilara (@marioncotilards) January 24, 2018
I can't believe Meryl Streep is joining the cast of Big Little Lies as Laura Dern's daughter!!!!— Bess Kalb (@bessbell) January 25, 2018
Meryl Streep— Jon (@prasejeebus) January 24, 2018
in Big Little Lies