Big Little Lies Season 2 hasn't been confirmed by HBO, and it doesn't seem likely that it will be.
To be perfectly honest, Big Little Lies Season 2 is a longshot. The HBO series is based on the novel of the same name by Liane Moriarty, and the show has already worked through that in its six episodes.
But while the show hasn't brought in quite the viewership that some of HBO's other dramatic offerings have, it has a wildly devoted and vocal fanbase. There's definitely an appetite for Big Little Lies Season 2 if HBO is willing to try and work something out with Liane Moriarty and David E. Kelley.
The problem, of course, is that the always reliable TV Linehas word from "multiple sources" that there are "no plans" to make Big Little Lies Season 2 a reality. But if Nicole Kidman and Reese Witherspoon are willing to figure things out with HBO and Liane Moriarty, and if the fans are vocal enough, maybe there will be a chance. If nothing else, Reese Witherspoon is apparently up for it.
So, we wouldn't necessarily hold our breath for Big Little Lies Season 2, but if you're determined to make it happen, you should tweet at HBO as often as possible and let them know that there's plenty of interest in a second season for the acclaimed drama with the incredible cast.