Lynskey's performance in the crime thriller I Don't Feel at Home in This World Anymore (2017) was roundly praised by critics.
The film's director (Macon Blair) wrote the character of Ruth, a downtrodden vigilante who teams up with her neighbor (played by Elijah Wood) to track down a burglar, specifically with Lynskey in mind.
The role proved to be physically challenging for her, as it involved a number of stunts and the use of prosthetics.
Peter Debruge of Variety felt that Lynskey delivered her "best work yet", while Time Out described her as "seething and magnetic".
The film was awarded the Grand Jury Prize at Sundance, while Lynskey received a nomination for the Gotham Independent Film Award for Best Actress.
That same year, she starred as the parent of a troubled teenager in the controversial drama And Then I Go; as a defense lawyer in the Australian miniseries Sunshine, for which she received a Golden Nymph Award nomination; as the mother of a girl with supernatural powers in The Changeover; and in the horror film XX, in which her character frantically tries to hide her husband's body after finding him dead.
In her review of the latter, Stephanie Zacharek of Time wrote, "The picture has a wry, comic charge, and Lynskey, terrific as always, brings a grace note of pathos to the wicked proceedings".

Lynskey had a starring role in the independent drama Sadie in 2018, playing a woman struggling to raise her daughter while her husband is on a tour of duty in Afghanistan.
Variety described the film as "quietly absorbing", adding that Lynskey's work was "strong" and "compelling"; while Frank Scheck of The Hollywood Reporter wrote, "It's no surprise that Lynskey, who has quietly [been] establishing herself as one of indie cinema's finest actors, is once again superb in her emotionally complex turn".
Next, she appeared as Molly Strand on the first season of Castle Rock, a psychological horror series based on characters and settings from the novels of Stephen King.
The series premiered on Hulu in July 2018 and garnered positive reviews, particularly for the cast; Paste referred to Lynskey as "delicately complex", while Alan Sepinwall of Rolling Stone felt the show was "the latest example of how much humanity and grounding [Lynskey] can bring to the most surreal and macabre of stories ... a tradition that goes back to when she was a teenager in Heavenly Creatures".
The series was later renewed for a second season; however, due to the anthological nature of the narrative, it featured a different set of actors.

Between April and May 2020, Lynskey co-starred with Cate Blanchett in the nine-part miniseries Mrs. America, a political drama centred on the career of conservative activist Phyllis Schlafly.
The series ran on FX on Hulu and was widely acclaimed by critics, with James Poniewozik of The New York Times calling it "breathtaking ... a meticulously created and observed mural that finds the germ of contemporary America in the striving of righteously mad women".
Lynskey's portrayal of the real-life Rosemary Thomson, a staunch supporter of Schlafly's, was described as "delightful" and a "standout" among the cast.
She later referred to working with Blanchett as "one of the great experiences of my life".
Lynskey's performance in the crime thriller I Don't Feel at Home in This World Anymore (2017) was roundly praised by critics. The film's director (Macon Blair) wrote the character of Ruth, a downtrodden vigilante who teams up with her neighbor (played by Elijah Wood) to track down a burglar, specifically with Lynskey in mind. The role proved to be physically challenging for her, as it involved a number of stunts and the use of prosthetics. Peter Debruge of Variety felt that Lynskey delivered her "best work yet", while Time Out described her as "seething and magnetic". The film was awarded the Grand Jury Prize at Sundance, while Lynskey received a nomination for the Gotham Independent Film Award for Best Actress. That same year, she starred as the parent of a troubled teenager in the controversial drama And Then I Go; as a defense lawyer in the Australian miniseries Sunshine, for which she received a Golden Nymph Award nomination; as the mother of a girl with supernatural powers in The Changeover; and in the horror film XX, in which her character frantically tries to hide her husband's body after finding him dead. In her review of the latter, Stephanie Zacharek of Time wrote, "The picture has a wry, comic charge, and Lynskey, terrific as always, brings a grace note of pathos to the wicked proceedings".
Lynskey had a starring role in the independent drama Sadie in 2018, playing a woman struggling to raise her daughter while her husband is on a tour of duty in Afghanistan. Variety described the film as "quietly absorbing", adding that Lynskey's work was "strong" and "compelling"; while Frank Scheck of The Hollywood Reporter wrote, "It's no surprise that Lynskey, who has quietly [been] establishing herself as one of indie cinema's finest actors, is once again superb in her emotionally complex turn". Next, she appeared as Molly Strand on the first season of Castle Rock, a psychological horror series based on characters and settings from the novels of Stephen King. The series premiered on Hulu in July 2018 and garnered positive reviews, particularly for the cast; Paste referred to Lynskey as "delicately complex", while Alan Sepinwall of Rolling Stone felt the show was "the latest example of how much humanity and grounding [Lynskey] can bring to the most surreal and macabre of stories ... a tradition that goes back to when she was a teenager in Heavenly Creatures". The series was later renewed for a second season; however, due to the anthological nature of the narrative, it featured a different set of actors.
Between April and May 2020, Lynskey co-starred with Cate Blanchett in the nine-part miniseries Mrs. America, a political drama centred on the career of conservative activist Phyllis Schlafly. The series ran on FX on Hulu and was widely acclaimed by critics, with James Poniewozik of The New York Times calling it "breathtaking ... a meticulously created and observed mural that finds the germ of contemporary America in the striving of righteously mad women". Lynskey's portrayal of the real-life Rosemary Thomson, a staunch supporter of Schlafly's, was described as "delightful" and a "standout" among the cast. She later referred to working with Blanchett as "one of the great experiences of my life".
Melanie Lynskey