Waste sorting at the source has been identified as a crucial solution for sustainable waste management in developing countries like Vietnam. Numerous previous studies have investigated the factors influencing waste sorting behavior among consumers. However, there has been limited research on consumers’ capability in waste sorting at source, particularly the role of information. Without sufficient consumer capability in waste sorting, contamination continues to be a widespread problem, posing a challenge to the sustainability of such programs. A survey using the ASK (Attitude-Skill-Knowledge) model was conducted with 228 participants in Lao Cai city, Vietnam, to assess how information enhances consumer capability in waste sorting. This study indicated that: (1) Both information quality and information accessibility could affect overall consumer capability toward waste sorting at the source; (2) Information accessibility is important in determining all ASK component, while interestingly, information quality plays an important role in determining consumers’ attitudes toward waste sorting at the source. The study suggested some solutions for enhancing consumer capability in waste sorting program, including engaging all stakeholders, leveraging technology, educational campaigns, and regular updates on waste sorting at the source information.