The incident happened yesterday evening.
Just after 6pm yesterday, a man armed with a knife entered the petrol station on Fax Bridge.
He was armed with a knife and demanded money from staff - before leaving the scene with a sum of cash.
Gardaí reviewed CCTV footage while uniform officers searched the area and began house to house inquiries.
A man in his 20s was arrested a short time later and brought to Bandon Garda Station.
He can be questioned for up to 24 hours.
