Antarctic sea ice is one of the largest ecosystems on Earth, most of which consists of annual pack ice, which contains various habitats for sea-ice algae to grow and fix carbon dioxide into biomass. Sea-ice biogeochemical models suggest that Antarctic pack ice contributes to a small but significant fraction of the primary production in the ice-covered area of the Southern Ocean. Actual measurements of primary production in Antarctic sea ice remain scarce and an observational estimate of primary production has not been revisited in over 30 years. A historical ice core dataset of particulate and dissolved organic carbon from 362 ice cores sampled between 1989 and 2019 was used to place observational constraints on sea-ice net community production. Our estimate of 26.8-32.2 Tg C year-1 accounts for 13-15% of the total primary production in the Antarctic sea-ice zone, and is in remarkable agreement with model estimates.