Background and Objectives: Sarcopenia is a significant concern in stroke rehabilitation, with a high prevalence reported in acute stroke patients. This study examines the effect of sarcopenia on rehabilitation outcomes in acute stroke patients. Materials and Methods: This study was conducted with acute stroke patients admitted within 90 days of onset to the rehabilitation hospital. Participants were divided into a stroke with sarcopenia group and a stroke without sarcopenia group. Evaluations were conducted at baseline, 4 weeks, and 8 weeks, including the following assessments: manual muscle testing (MMT), Berg Balance Scale (BBS), functional ambulation category (FAC), and Modified Barthel Index (MBI). Both groups received an identical rehabilitation program for 8 weeks. Results: Significant within-group improvements were observed in both groups across all measures (p < 0.05). However, the stroke with sarcopenia group showed significantly less improvement in MMT, BBS, FAC, and MBI compared to the stroke without sarcopenia group at both 4 and 8 weeks (p < 0.05). Conclusions: These results underscore the significant impact of sarcopenia on functional recovery in stroke patients, despite both groups receiving identical rehabilitation programs. The presence of sarcopenia was a critical predictor of poorer outcomes in muscle strength, balance, ambulation, and activities of daily living. Given these findings, specific rehabilitation strategies targeting sarcopenia are needed to improve recovery in stroke patients. Future research should include larger sample sizes, longer follow-ups, and sarcopenic patient-specific rehabilitation programs.