Background: Kratom use in the West has increased recently, yet the prevalence and motives for use among individuals with a history of substance use disorder (SUD) have not been fully examined. Kratom has been documented as a means of treating chronic pain, mitigating drug dependence, and easing withdrawal symptoms, yet it is unclear if substance users are utilizing kratom as a self-medication. Abuse liability, side effects, and overall appeal of kratom remain uncertain. Methods: In April 2017, an anonymous survey regarding kratom use and motivations was completed by clients enrolled in a 12-Step-oriented residential program. 500 respondents with a self-reported history of SUD completed the survey. Results: 20.8% of respondents endorsed lifetime kratom use and 10.2% reported past-12-month use. Kratomusers were younger (= 32.1 vs. 35.9, p < 0.001) and were more versatile substance users. A majority (68.9%) of kratom-users reported having used the drug as a means of reducing or abstaining from non-prescription opioids (NPO) and/or heroin, and 64.1% reported using kratom as a substitute for NPO/heroin. 18.4% of kratom-users reported using the drug due to a disability or chronic pain. One-third of kratom-users stated that kratom was a helpful substance and that they would try it again. However, kratom was not preferred and was indicated as having less appeal than NPO, heroin, amphetamines, and Suboxone. Conclusions: Among substance users, kratom use may be initiated for a variety of reasons, including as a novel form of harm-reduction or drug substitution, particularly in the context of dependence and withdrawal from other substances.