Police were called to a collision involving a lorry and car on the westbound carriageway, which resulted in the carriageway shutting with emergency services at the scene.
The road was re-opened less than an hour later.
It is understood that nobody was injured in the incident.
A North Wales Police spokesperson said: “We were called at 3.26pm yesterday reporting a road traffic collision involving a lorry and a car on the Westbound carriageway of the A55 at the Conwy tunnel.
“Officers attended and the road was closed until 4.10pm.”
