The δ¹⁸O ratio in speleothems is a proxy for many different climate variables. Here, we present δ¹⁸O reconstructions at sub-annual resolution timescales spanning the early-Holocene period (i.e., 9.03 to 8.84 ka) from a speleothem sample collected from a cave site located within the core sink region of the East African monsoon (EAM). The δ¹⁸O time series documents persistent decadal and interdecadal scale variability throughout the growth period, spanning the classic El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) bandwidths (i.e., 2–7 years). The observed variability in the stalagmite δ¹⁸O time series suggests that the Eastern African monsoon system is regulated by the ENSO and the Indian Ocean Dipole (IOD), similar to the present-day conditions. The observed range of δ¹⁸O values is larger than any inter-annual and decadal variation observed in the modern-time reconstructions from the same cave, indicating increased East African monsoon variability than it observed today. However, further investigation should investigate whether monsoon intensity changes or other factors exclusively govern the observed δ¹⁸O variability.