Although strong evidence exists about the effectiveness of basic childbirth services in reducing maternal and newborn mortality, these services are not provided in every childbirth, even those at health facilities. The WHO Safe Childbirth Checklist (SCC) was developed as a job aide to remind health workers of evidenced-based practices to be provided at specific points in the childbirth process. The Zambian government requested context-specific evidence on the feasibility and outcomes associated with introducing the checklist and related mentorship. A study was conducted on use of the SCC in four facilities in Nchelenge District of Zambia. Observations of childbirth services were conducted just before and six months after the introduction of the intervention. Observers used a structured tool to record adherence to essential services indicated on the checklist. The primary outcome of interest was the change in the average proportion of essential childbirth practices completed. Feedback questionnaires were administered to health workers before and six months after the intervention. At baseline and endline, 108 and 148 pause points were observed, respectively. There was an increase from 57% to 76% of tasks performed (p = 0.04). Considering only these cases where necessary supplies were available, health workers completed 60% of associated tasks at baseline compared to 84% at endline (p<0.01). Some tasks, such as taking an infant's temperature and hand washing, were never or rarely performed at baseline. Feedback from the health workers indicated that nearly all health workers agreed or strongly agreed with positive statements about the intervention. The performance of health workers in Zambia in completing essential practices in childbirth was low at baseline but improvements were observed with the introduction of the SCC and mentorship. Our results suggest that such interventions could improve quality of care for facility-based childbirth. However, national-level commitment to ensuring availability of trained staff and supplies is essential for success. Trial registration Clinical Trials.gov (NCT03263182) Registered August 28, 2017 This study adheres to CONSORT guidelines.