We report here new field and analytical data from Precambrian rocks on Hainan Island of the Cathaysia Block, south China, and examine its probable connection to Laurentia. Granitoids and newly discovered felsic volcanic rocks dated at 1433 ± 6 Ma and 1439 ± 9 Ma (SHRIMP U‐Pb zircon) on Hainan Island are coeval with, and isotopically similar to the 1500–1350 Ma trans‐continental granite‐rhyolite province in southern Laurentia. Quartzites unconformably overlying the ca. 1430 Ma volcaniclastic rocks on Hainan Island are interpreted as locally‐sourced Grenvillian foreland basin deposits that can be correlated with the Deer Trail Group of south‐western Laurentia. The detrital provenance of the quartzites contains age populations comparable to the 1610–1490 Ma, westerly‐sourced non‐Laurentian detrital grains reported in the Belt Basin of south‐western Laurentia. Our new data thus make Cathaysia the most likely continental block next to western Laurentia before and during the late Mesoproterozoic assembly of Rodinia.