Poynton was born in 1970 in Durban, and lives in Cape Town. A survey of 25 years of her painting, titled Model for a World, showed at The New Church Museum, Cape Town, in mid-2014. She has held nine solo exhibitions at Stevenson, most recently The Human Abstract in Johannesburg (2018) and, prior to this, Picnic in Cape Town (2016). She showed at the KZNSA Gallery, Durban, in 2010, and held her first US solo exhibitions at the Savannah College of Art and Design's galleries in Savannah and Atlanta in 2009. You, Me, There, Here, a solo exhibition of works by the artist shows at the Institute of Contemporary Art Indian Ocean in Mauritius.
Group exhibitions include the Sharjah Biennial (2017); Der Feine Riss: Zeitgenössische Malerei auf dem Historischen Feld (The Subtle Rift: Contemporary Painting in the Historical Frame) at Haus am Lützowplatz, Berlin (2016); Home Truths: Domestic Interiors from South African Collections at the Iziko South African National Gallery (2016); I Love You Sugar Kane, Institute of Contemporary Art Indian Ocean, Port Louis, Mauritius (2016); Eros and Thanatos, SOR Rusche Collection, Oelde/Berlin (2012); Von Liebeslust und Lebenslast - der inszenierte Alltagat, Corvey Castle, near Höxter, Germany (2009); and What lies beneath, Galerie Mikael Andersen, Copenhagen (2006).
Two monographs have been published on her paintings: Everything Matters (SCAD/Stevenson, 2009) and Pictures (Stevenson, 2013).