Lucy Horobin began radio presenting at Trent FM alongside Jason King, and then with Rich Clarke on the evening show which was branded Rich and Luce. Lucy Horobin and Clarke then moved to Bauer Radio owned Key 103 to present In:Demand, which later became networked on Bauer Place stations in the North of England, and digital station The Hits Radio. In November 2011 she left In:Demand.
On 23 January 2012 Lucy Horobin and Jason King debuted as presenters of Heart Breakfast on Heart Solent. From 4 August 2012 the duo have also presented Saturday breakfast on Heart. From 13 until 29 August 2012 she and King presented Heart Breakfast on Heart London, in the absence of Harriet Scott and Jamie Theakston, meaning they were absent from their usual show on Heart Solent. In January 2013, Lucy along with Jason King moved to Heart London to present weekday drivetime along with networked Saturday breakfast.