| Year | Award | Category | Nominated work | Result | Ref. |
| 2009 | London Film Festival Awards | Best British Newcomer | The Scouting Book for Boys | Won | |
| 2010 | Edinburgh Fringe Festival | Fringe First | Bunny | Won | |
| 2015 | Drama Desk Awards | Outstanding Play | Let the Right One In | Nominated | |
| 2016 | Jameson Empire Award | Best TV Series | This Is England '90 | Won | |
| 2017 | Biarritz International Festival of Audiovisual Programming | TV series and Serials: Screenplay | National Treasure | Won | |
| Olivier Awards | Best New Play | Harry Potter and the Cursed Child | Won | |
| Evening Standard Theatre Awards | Best Play | Won | |
| 2018 | Tony Awards | Best Play | Won | |
| Broadcast Film Critics Association Awards | Best Adapted Screenplay | Wonder | Nominated | [better source needed] |
| 2020 | Drama Desk Awards | Outstanding Adaptation | A Christmas Carol | Won | |
| Broadcasting Press Guild Awards | Best Writer | The Virtues | Nominated | |
| Best Writer | His Dark Materials | Nominated | |
| 2021 | Prix Italia | TV Performing Arts | Crip Tales | Won | |
| Rose d'Or | Best Drama | Help | Won | |
| 2022 | Sandford St Martin Awards | Radio Times Readers' Award | Nominated | |
| Banff Rockie Award | Best Feature Length Film | Won | |
| Rockies Grand Jury Prize | Won | |
| Venice TV Awards | Best TV Film | Won | |
| Seoul International Drama Awards | Best TV Movie | Won | |
| International Emmy Awards | Best TV Movie / Mini Series | Won | |
| C21 Drama Awards | Best TV Movie | Nominated | |
| 2023 | National Film and Television School | Honorary Fellowship | | Won | |
| Banff Rockie Award | Best Feature Length Film | Then Barbara Met Alan | Nominated | |
| Evening Standard Theatre Awards | Best Play | The Motive and the Cue | Won | |
| WhatsOnStage Awards | Best New Play | Nominated | |
| 2024 | Banff Rockie Award | Best Limited Series | Best Interests | Won | |
| Critics' Circle Theatre Awards | Best New Play | The Motive and the Cue | Won | |
| Olivier Awards | Best New Play | Nominated | |
| 2025 | Gotham TV Awards | Breakthrough Limited Series | Adolescence | Won | |
| The Astra Awards | Best Limited Series | Won | |
| The Astra Awards | Best Writing in a Limited Series or TV Movie | Won | |
| Edinburgh TV Awards | Best Drama | Won | |
| TCA Awards | Program of the Year | Nominated | |
| TCA Awards | Outstanding Achievement in Movies, Miniseries or Specials | Won | |
| Emmy Awards | Limited or Anthology Series | Won | |
| Emmy Awards | Outstanding Writing For A Limited Or Anthology Series Or Movie | Won | |
| Seoul International Drama Awards | Best Miniseries | Nominated | |
| Seoul International Drama Awards | Best Screenwriter | Nominated | |
| Seoul International Drama Awards | Grand Prize | Won | |
| National Television Awards | New Drama | Won | |
| Sky Arts Awards | Best Television | Won | |
| Rose d’Or | Drama | Won | |
| Rose d’Or | The Golden Rose | Won | |
| Film Independent Spirit Awards | Best New Scripted Series | Nominated | |
| American Film Institute Awards | Top 10 Television Programs | Won | |