Purpose The purpose of this study was to develop an intervention targeting employers, with the aim of enhancing cancer survivors' return to work (RTW). Methods Intervention Mapping was used to combine information gathered from several procedures involving numerous stakeholders, for example, employers, cancer survivors, oncological occupational physicians, and e-health experts. Results Employers indicated that they require tailored support during four RTW phases: (1) disclosure, (2) treatment, (3) RTW planning, and (4) actual RTW. The most important employer actions were identified for each RTW phase, for instance, "communicate," "support practically," and "assess work ability," and thereafter formulated as the performance objectives of the intervention. The trans-theoretical model of change was used as a theoretical framework, and several methodologies were employed to induce the desired behavior change, for example modeling, tailoring, and active learning. Subsequently, a webbased intervention with interactive videos, conversation checklists, links to reliable external sources, and succinct, tailored tips and information was developed and adjusted on the basis of pre-tests with different stakeholders. Conclusions The intervention was developed with input from employers and all relevant stakeholders in the RTW of cancer survivors. The systematic, step-wise development resulted in a succinct and easily accessible intervention targeting the most important employer actions during all RTW phases. As such, the intervention corresponds with employers' needs and preferences in practice. Implications for cancer survivors By providing employers with support, the intervention could well be the missing link in efforts to optimize the work participation of cancer survivors.