Strategic planning is widely recognized as a critical managerial process that enables organizations to align internal resources with external environmental demands and achieve sustainable growth. While extensive research exists on strategic planning in large firms, limited attention has been given to how service-sector micro, small, and medium enterprise (MSME) startups implement strategic planning, particularly in emerging economies. This study examined strategic planning practices among service-sector MSME startups in Nairobi County, Kenya. Guided by the McKinsey 7S Model and Dynamic Capabilities Theory, the study adopted a descriptive cross-sectional design. Data were collected using structured questionnaires administered to founders, owners, and managers of service-based MSME startups, yielding 156 valid responses, a 76% response rate. Findings reveal that although most startups initially lacked documented strategic plans, a majority later implemented formal planning practices. Key practices included environmental scanning, documentation of vision, mission, and goals, top-management-led strategy formulation, communication of strategy to employees, and periodic monitoring and evaluation. Persistent challenges included limited employee involvement and insufficient resource allocation. The study concludes that service-sector MSME startups increasingly recognize the importance of strategic planning, offering practical insights for entrepreneurs, policymakers, and scholars seeking to strengthen strategic management practices in emerging economies.