Collective motivational interviewing (CMI) is a novelty motivational approach which optimises the motivational interviewing (MI) for individuals from collectivistic cultures. While MI has been empirically tested as an effective intervention for addictive disorders and has had a positive effect on facilitating lifestyle changes, CMI has retained the potency of MI as an individualistic intervention, and it further invites the social network resources to strengthen the level of motivation and cultivate a joint change partnership. This pilot study was the first clinical study of CMI to work with individuals with drug use problems (IDUPs) by involving concerned significant others (CSOs) in the three-session intervention, and the fidelity control was assessed by the Collective Motivational Interviewing Treatment Integrity (CMITI) scale. This pre-post–follow-up and uncontrolled feasibility study was conducted between 2017 and 2019, with dyads of 20 IDUPs and their CSOs. The potential impacts of CMI were examined by measures at baseline, post-intervention, and 1-month and 3-month post-intervention. All clinical sessions were audio-recorded, and four cases were randomly selected for fidelity review by two trained coders. The normality of data at the baseline was checked by a Shapiro–Wilk test. Non-parametric Wilcoxon-signed-rank test and repeated-measures ANOVA were employed for quantitative analysis. The results showed that six IDUPs had reduced drug use, and ten maintained drug abstinence with the support of CSOs, whereas four IDUPs remained unchanged or increased drug use. Overall, at the 3-month follow-up, drug use was reduced (p > 0.05), social support was strengthened (p < 0.05), and the IDUPs’ motivation for change was enhanced (p < 0.05). However, the small sample sizes, non-random sampling, and lack of control group may limit the generalizability and confirmation of the outcomes and of the “real effects”. This finding of the study suggests that the CMI is a feasible and acceptable therapeutic tool to motivate IDUPs with the support of CSOs to achieve mutually agreed-upon goals. Further development and evaluation with robust methodology are warranted.