Geoduck clams (Panopea generosa Gould 1850) are large, deep-burrowing bivalves distributed from southeast Alaska to Baja California. This species supports a lucrative fishery in the states of Washington and Alaska, as well as in British Columbia, Canada, and geoduck aquaculture currently supplies approximately 30% of the market. To manage this species effectively, it is important to elucidate the population age structure. Geoduck ages are currently estimated by counting valve growth rings. We used bomb radiocarbon (¹⁴C) to validate geoduck age estimates derived from counts of growth bands in thin-sectioned valve inner hinge plates. Seven specimens with presumed birth years before, during, and after the bomb testing period (1957 to 1967) were sampled from the first 3–5 y of growth, and subsequently assayed for ¹⁴C using accelerator mass spectrometry. The ¹⁴C values from each of our specimens compared with reference ¹⁴C chronologies for the northeast Pacific were in accord at estimated birth years. The temporal concordance validates current age estimation methods, and provides a first record of marine bomb radiocarbon in Puget Sound.