The store, based in Swan Walk Shopping Centre, will shut down at the beginning of February.
It came to Horsham as a pop-up shop to test the waters for long-term business.
Sales assistant Vicki Scallan, 18, said: “Ollie & Nic is sad to say that we are leaving this town. We would like to thank you for all your custom.
“If you want to make the most of our January sales please come down and say goodbye.”
The company has six stores across the country - including one in Brighton and two in London.