Background Subclinical myocardial injury in form of hs‐cTn (high‐sensitivity cardiac troponin) levels has been associated with cognitive impairment and imaging markers of cerebral small vessel disease (SVD) in population‐based and cardiovascular cohorts. Whether hs‐cTn is associated with domain‐specific cognitive decline and SVD burden in patients with stroke remains unknown. Methods and Results We analyzed patients with acute stroke without premorbid dementia from the prospective multicenter DEMDAS (DZNE [German Center for Neurodegenerative Disease]‐Mechanisms of Dementia after Stroke) study. Patients underwent neuropsychological testing 6 and 12 months after the index event. Test results were classified into 5 cognitive domains (language, memory, executive function, attention, and visuospatial function). SVD markers (lacunes, cerebral microbleeds, white matter hyperintensities, and enlarged perivascular spaces) were assessed on cranial magnetic resonance imaging to constitute a global SVD score. We examined the association between hs‐cTnT (hs‐cTn T levels) and cognitive domains as well as the global SVD score and individual SVD markers, respectively. Measurement of cognitive and SVD‐marker analyses were performed in 385 and 466 patients with available hs‐cTnT levels, respectively. In analyses adjusted for demographic characteristics, cardiovascular risk factors, and cognitive status at baseline, higher hs‐cTnT was negatively associated with the cognitive domains “attention” up to 12 months of follow‐up (beta‐coefficient, −0.273 [95% CI, −0.436 to −0.109]) and “executive function” after 12 months. Higher hs‐cTnT was associated with the global SVD score (adjusted odds ratio, 1.95 [95% CI, 1.27–3.00]) and the white matter hyperintensities and lacune subscores. Conclusions In patients with stroke, hs‐cTnT is associated with a higher burden of SVD markers and cognitive function in domains linked to vascular cognitive impairment. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01334749.