This dataset comprises palynological counts on sediments from IODP Expedition 374 Site U1521 to the Ross Sea, collected on the RV JOIDES Resolution. Marine palynomorphs are counted in 23 samples, and 7 samples were counted for terrestrial palynomorphs (pollen and spores). Shipboard biostratigraphy and magnetostratigraphy suggests the samples are early Miocene in age (McKay et al., 2019, Proceedings of the International Ocean Discovery Program).