Objectives As unrecorded alcohol use contributes to a substantial burden of disease, this study characterises this phenomenon in newly independent states (NIS) of the former Soviet Union with regard to the sources of unrecorded alcohol, and the proportion of unrecorded of total alcohol consumption. We also investigate associated sociodemographic characteristics and drinking patterns. Design Cross-sectional data on overall and unrecorded alcohol use in the past 7 days from WHO STEPwise Approach to NCD Risk Factor Surveillance (STEPS) surveys. Descriptive statistics were calculated at the country level, hierarchical logistic and linear regression models were used to investigate sociodemographic characteristics and drinking patterns associated with using unrecorded alcohol. Setting Nine NIS (Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Republic of Moldova, Tajikistan, Turkmenistan and Uzbekistan) in the years 2013-2017. Participants Nationally representative samples including a total of 36 259 participants. Results A total of 6251 participants (19.7%; 95% CI 7.9% to 31.5%) reported alcohol consumption in the past 7 days, 2185 of which (35.1%; 95% CI 8.2% to 62.0%) reported unrecorded alcohol consumption with pronounced differences between countries. The population-weighted average proportion of unrecorded consumption in nine NIS was 8.7% (95% CI 5.9% to 12.4%). The most common type of unrecorded alcohol was home-made spirits, followed by home-made beer and wine. Older (45-69 vs 25-44 years) and unemployed (vs employed) participants had higher odds of using unrecorded alcohol. More nuanced sociodemographic differences were observed for specific types of unrecorded alcohol. Conclusions This contribution is the first to highlight both, prevalence and composition of unrecorded alcohol consumption in nine NIS. The observed proportions and sources of unrecorded alcohol are discussed in light of local challenges in policy implementation, especially in regard to the newly formed Eurasian Economic Union (EAEU), as some but not all NIS are in the EAEU.