Herdlefjorden is a fjord in Hordaland county, Norway. The long fjord runs between the islands of Holsnøy (in Meland municipality) and Askøy (in Askøy municipality). The fjord connects with the Salhusfjorden and the Byfjorden on the southeast end and it flows out into the Hjeltefjorden on the northwest end of the fjord. The fjord is named after the island of Herdla, located at the northern end of the fjord.