Background <p>Rifampicin-resistant tuberculosis (RR-TB) threatens global TB control; diagnostic delays worsen transmission and outcomes. Evidence on delays in high-burden settings is limited. This study quantified patient, health-system, and total diagnostic delays among RR-TB patients in Guizhou Province, China (2019–2023) and identified factors associated with prolonged delays to inform targeted control measures.</p> Methods <p>We included 2,677 RR-TB patients diagnosed and registered in Guizhou from 2019 to 2023. The status of three types of delays at different levels was investigated. Group comparisons used chi-square tests; temporal trends were evaluated with chi-square trend tests. Binary logistic regression models identified independent predictors of prolonged delays at multiple cutoffs.</p> Results <p>Median delays were 32 days (<i>IQR</i> 3–118) for patient delay, 15 days (<i>IQR</i> 2–62) for health system delay, and 86 days (<i>IQR</i> 32–261) for total delay. From 2019 to 2023, health system and total delay rates declined significantly (<i>P</i> &lt; 0.05), whereas patient delay rates showed no significant temporal change (<i>P</i> &gt; 0.05). At a 14-day cutoff, patient delay was highest in Qianxinan Prefecture (75.0%, <i>P</i> &lt; 0.05); health system and total delay rates were highest in Qiandongnan Prefecture (73.7% and 88.9%, respectively; <i>P</i> &lt; 0.05). Multivariable analysis indicated that referral/recommend (<i>OR</i> = 1.44), comorbidities (<i>OR</i> = 1.51), initial treatment failure (<i>OR</i> = 1.32), and combined extrapulmonary TB (<i>OR</i> = 1.50) were independently associated with patient delay &gt; 14 days; returned patients (<i>OR</i> = 1.84) and other registration classifications (<i>OR</i> = 1.39) predicted delays &gt; 60 days. For health system delay, students (<i>OR</i> = 1.73) and migrant populations (<i>OR</i> = 3.39) had an increased risk at &gt; 14 days, while initial treatment failure (<i>OR</i> = 1.45) and other registration classifications (<i>OR</i> = 1.98) were significant at &gt; 60 days. For total delay, migrant populations (<i>OR</i> = 1.90), comorbidities (<i>OR</i> = 1.34), initial treatment failure (<i>OR</i> = 1.94), and other registration classifications (<i>OR</i> = 1.51) were key predictors.</p> Conclusion <p>Although progress has been made in reducing diagnostic delays for RR-TB in Guizhou Province, rising patient delay rates and significant regional disparities persist. Strengthening primary healthcare capacity, establishing active tracing and follow-up mechanisms, optimizing migrant population management, implementing revisit reminders for patients with initial treatment failure, and accelerating the deployment of molecular drug susceptibility testing are recommended to enhance early diagnosis and treatment outcomes, thereby advancing the global goal of ending tuberculosis by 2035.</p> Clinical trial number <p>Not applicable.</p>