The following year she took two productions of her second play, Geronimo to the Edinburgh Fringe, under the title The Umbilical Project. The two plays, Cut and Uncut, were an experiment in cutting the cord between writer and production. Uncut was directed by Kirkwood herself and Cut by a completely separate company under the direction of Matt Addicott. No contact was made between the two companies during the rehearsal period, prompting the tag line "Two casts, two crews, two directors, two venues, one new play... no communication". Her third play Guns or Butter, about soldiers being overcome by the horror of war, was written for the Terror 2007 Festival at the Union Theatre, London. Tinderbox, a dark comedy set in a fictional 21st CenturyEngland, premiered at the Bush Theatre in 2008. It starred Jamie Foreman and Sheridan Smith. In the same year she also contributed to the Bush's 50 Ways To Leave Your Lover. Her version of Ibsen's Hedda Gabler, titled Hedda, premiered at London's Gate Theatre in 2008 to favourable reviews. Kirkwood's promenade play about sex trafficking, It Felt Empty When The Heart Went At First But It Is Alright Now, was produced by Clean Break Theatre at the Arcola Theatre. Her short horror piece Psychogeography premiered at the Bush in 2008 and was revived at Southwark Playhouse. In 2010, a fresh and humourous version of was devised by Lucy Kirkwood and director Katie Mitchell and written by Kirkwood. It premiered at the National Theatre in London as Christmas show in December, 2010. Her play NSFW premiered at the Royal Court Theatre, starring Janie Dee and Julian Barrett and directed by Simon Godwin, in October 2012. Her play Chimerica examines the relationship between the US and China since the Tiananmen Square protests through the eyes of a former activist, and features over forty scene changes and British-Chinese actors. The play opened at the Almeida Theatre in May 2013 and transferred to the West End in August 2013. The play's title echoes the portmanteau word 'Chimerica', invented by economists to define the intertwined economies of the US and China. The play won 2014 Olivier Awards for best new play, best director, best lighting, best sound and best set design. Kirkwood's play The Children opened at the Royal Court Theatre in November 2016, directed by James Macdonald and starring Ron Cook, Francesca Annis and Deborah Findlay, receiving positive reviews from critics. The production transferred to the Samuel J. Friedman Theatre on Broadway in November 2017, officially on 12 December 2017, with its original cast. The play was nominated for the 2018 Outer Critics Circle Award as Outstanding New Broadway Play. The play was nominated for the 2018 Tony Award for Best Play and the Tony Award, Best Performance by an Actress in a Featured Role in a Play. Rufus Norris directed her stage playMosquitoes, which illustrates family disputes between sisters by referencing collisions in experimental physics, at London's National Theatre in 2017. Kirkwood received a commissioning grant from the Manhattan Theatre Club to write the play. Thomas Bockelmann directed Mosquitoes at the German Staatstheater Kassel on 30 August 2018 as a three hour stage production. Kirkwood's next play is titled The Welkin and concerns the case of a woman convicted of murder. She claims to be pregnant, preventing a death sentence being carried out. The play revolves around a group of 12 matrons assembled to determine the truth of her claim. The Welkin was performed at London's National Theatre in the first half of 2020.
Screenwriting
Kirkwood wrote an episode for each of the second, third, and fourth series of Skins, broadcast between 2008 and 2010. In 2014, her drama series The Smoke, made by Kudos, was televised on Sky 1. It follows the exploits of white watch at a fictional London fire station. She adapted her play Chimerica into a four-part miniseries for Channel 4, broadcast in 2019, and for the same network has written a new four-part series Adult Material, following a woman's life in the adult film industry, due to be shown in 2020.