Organosilicon substances are ubiquitous in the environment due to their stability and numerous applications in consumer products. Therefore, it is desirable to reduce their environmental persistency. Our study aimed to better understand the impact of silicon atoms in organic compounds on their environmental biodegradability as a contribution to sustainable chemistry. Accordingly, we investigated the biodegradability of organosilicon compounds and their carbon analogues. OECD 301D test was used to assess ready biodegradability. In addition, GC-MS analyses were performed to study the fate of the compounds in the test. Three out of five carbon compounds and no organosilicon compound were found readily biodegradable. In all but one case, higher biodegradation degrees could be observed for the carbon compounds. Hydrolysis was identified as a mandatory step prior to the biodegradation of organosilicon substances. The silicon-free product of hydrolysis determined the rate of biodegradation. The silicon-containing reaction products of hydrolysis were not biodegradable. The high biodegradability of one organosilicon compound can be attributed to faster hydrolysis due to an easily hydrolysable Si–N bond and a high biodegradation rate of the resulting silicon-free hydrolysis product. Insertion of such heteroatoms or functional groups into polysiloxane chains may be a promising approach to benign organosilicon compounds.