Abstract Background and aim There are a paucity of studies investigating workforce affiliation in connection with first-time implantable cardioverter defibrillator (ICD)-implantation. This study explored workforce affiliation and risk markers associated with not returning to work in patients with ICDs. Methods Using the nationwide Danish registers, patients with a first-time ICD-implantation between 2007 and 2017 and of working age (30–65 years) were identified. Descriptive statistic and logistic regression models were used to describe workforce affiliation and to estimate risk markers associated with not returning to work, respectively. All analyses were stratified by indication for implantation (primary and secondary prevention). Results Of the 4659 ICD-patients of working age, 3300 patients (71%) were members of the workforce (employed, on sick leave or unemployed) (primary: 1428 (43%); secondary:1872 (57%)). At baseline, 842 primary and 1477 secondary prevention ICD-patients were employed. Of those employed at baseline, 81% primary and 75% secondary prevention ICD-patients returned to work within 1 year, whereof more than 80% remained employed the following year. Among patients receiving sick leave benefits at baseline, 25% were employed after 1 year. Risk markers of not returning to work were ‘younger age’ in primary prevention ICD-patients, while ‘female sex’, left ventricular ejection fraction ‘LVEF ≤40’, ‘lower income’, and ‘≥3 comorbidities’ were risk markers in secondary prevention ICD-patients. Lower educational level was a risk marker in both patient groups. Conclusion High return-to-work proportions following ICD-implantation, with a subsequent high level of employment maintenance were found. Several significant risk markers of not returning to work were identified including ‘lower educational level’ that posed a risk in both patient groups. Trial registration number Capital Region of Denmark, P-2019-051.