Background/Objectives: Evidence-based clinical guidelines and standardized nursing documentation are essential for healthcare quality and safety, yet evidence on their use by nurses in Kazakhstan is limited. This study assessed the reported use of clinical guidelines and nursing documentation checklists. Methods: A cross-sectional online survey with convenience sampling was conducted from December 2021 to February 2022; 2263 practicing nurses were analyzed. “Use” meant self-reported use in routine practice. Proportions with 95% confidence intervals were calculated for the whole sample. Results: Reported use varied across clinical areas. Pressure ulcer guidelines were used most often (39.0%; 95% CI 37.0–41.0), followed by patient- and family-centered care (37.1%), fall prevention (34.3%), and anti-smoking interventions (31.3%). Among documentation checklists, reported use was highest for allergic reaction care (40.3%) and preventing injuries and falls (34.5%) and below 15% for care after a tracheostomy, duodenal probing, and gastric tube insertion in neonates and premature infants, which apply only to specific patient groups. Conclusions: In this convenience sample, reported use of guidelines and checklists was low to moderate and uneven. The findings are not national implementation rates. The study design does not allow the causes of this variability to be identified; the role of education, organizational support, and electronic documentation should be examined in future research.