In 2009, O'Flynn appeared with Russell Tovey at London's Royal Court Theatre in Molly Davies' A Miracle. Michael Billington gave the play 3 stars out of five in his review for British newspaper The Guardian, finding that "Kate O'Flynn's Amy is a model of gawky despair" but concluding that the cast "fill out a play that provides plenty of evidence of youthful talent but that also leaves you wanting more". In the Evening Standard, Nicholas de Jongh praised O'Flynn's "beautiful rendering of passivity, selfishness and vulnerability", while The Daily Telegraph's Charles Spencer wrote, "Kate O'Flynn brings an astonishingly raw vulnerability to the stage as Amy, the tears streaming down her face as she describes how impossible she finds it to love and nurture her child".