Background <p>Few studies have examined the associations of sarcopenia, frailty, and sleep quality (SQ) trajectories among middle-aged and older Chinese adults. Our aim was to investigate these relationships using a nationally representative longitudinal study.</p> Methods <p>The study utilized 2011–2015 data from the China Health and Retirement Longitudinal Study (CHARLS), focusing on individuals aged 45 years and above. Sarcopenia and frailty were assessed at baseline. SQ was evaluated biennially via interview-based assessments from 2011 to 2015, with SQ scores calculated accordingly. A group-based trajectory model was applied to analyze the aging trajectory of SQ over time, while multinomial logistic regression was used to examine the associations between sarcopenia and frailty with SQ trajectory membership.</p> Results <p>Among 8,918 participants aged 45 years and older at baseline, trajectory analysis based on overall SQ scores identified four longitudinal patterns of SQ: “high sleep disorder trajectory” (<i>n</i> = 999, 11.20%), “moderate sleep disorder trajectory” (<i>n</i> = 3,714, 41.64%), “mild sleep disorder trajectory” (<i>n</i> = 2,197, 24.64%), and “low sleep disorder trajectory” (<i>n</i> = 2,008, 22.52%). After adjusting for demographic, behavioral, and health confounders, both sarcopenia and frailty were significantly and positively associated with mild, moderate, and high sleep disorder trajectories (all OR &gt; 1, all 95% CI excluded 1, all <i>P</i> &lt; 0.05).</p> Conclusion <p>These findings suggested that sarcopenia and frailty were negatively associated with SQ trajectories.</p>