We characterize heat dissipation of supported molybdenum disulfide (MoS 2 ) monolayers grown by chemical vapor deposition by means of ambient-condition scanning thermal microscopy (SThM). We find that the thermal boundary conductance of the MoS 2 monolayers in contact with 300 nm of SiO 2 is around 4.6 ± 2 MW m −2 K −1 . This value is in the low range of the values determined for exfoliated flakes with other techniques such as Raman thermometry, which span an order of magnitude (0.44–50 MW m −2 K −1 ), and underlines the dispersion of measurements. The sensitivity to the in-plane thermal conductivity of supported MoS 2 is very low, highlighting that the thermal boundary conductance is the key driver of heat dissipation for the MoS 2 monolayer when it is not suspended. In addition, this work also demonstrates that SThM calibration using different thicknesses of SiO 2 , initially aimed at being used with bulk materials can be extended to 2D materials.