Horner has exhibited nationally and internationally and has also had a number of solo exhibitions around England: Open Studio Exhibition, University for the Creative Arts, Farnham, Surrey (2016) Sculptural Painting Configurations, The Royal Marsden Hospital, Sutton, Surrey (2018) and Remnants from Ewhurst, Surrey,
The Old Diorama Arts Centre Gallery, 201 Drummond St, Regent’s Place, London (2019). Selected group exhibitions have been at The Redchurch St Gallery, The OXO Tower - Bargehouse, Lewisham Arthouse, The Melia White House, Safehouse 2, The Lethaby Gallery, The National Army Museum, The Fitzrovia Gallery,
The Cello Factory, The Shard, The Jeannie Avent Gallery and The Offshoot Gallery. Horner received the JPES Partnership prize at The London Group Open Exhibition in 2019 and was elected by The London Group Membership Committee to become a member in 2020, and his works have been collected in various private collections.