Antarctica’s basal water system contains more than 130 active lakes, and its evolution remains a major uncertainty in future ice sheet dynamics. Most of our current understanding has come from using satellite radar and laser altimetry acquired since 2003. NASA’s ICESat-2 laser altimetry mission, launched in September 2018, provides a new, small-footprint altimetry data set with which to investigate Antarctic active subglacial lake processes. Here, we demonstrate the ability to continue monitoring active subglacial lakes at timescales shorter than the ICESat-2’s repeat cycle and generate self-consistent time series of subglacial lake surface-height anomalies from combined ICESat, CryoSat-2, and ICESat-2 altimetry. Focusing on three regions with the known significant lake activity, we show that ICESat-2 laser altimetry can not only extend the record of subglacial lake activity but also provides better understanding of hydrological processes by capturing denser and more precise spatial detail.