Top-emitting, oxide-confined, polyimide-planarized 980-nm VCSELs with copper-plated heatsinks were fabricated and characterized. Increasing the plated heatsink radius from 0-μm to 4-μm larger than the mesa diameter for lasers with 8-μm oxide aperture diameter reduced the measured thermal impedance, increased the maximum bias current density, and increased the maximum output optical power achieved by a 29%, 37%, and 73%, respectively. VCSELs with oxide aperture diameter and heatsink overlap of 8-μm and 4-μm, respectively, demonstrated 17°C decrease in the internal device temperature (i.e. active region temperature) at the maximum output optical power. Devices with similar mesa diameters of 26-μm and different heatsink overlaps exhibited a threshold bias current and a total series resistance of (630±4%)μA and ∼95Ω, respectively.