Shortage of nurses negatively influences the working environment in hospitals, by placing extra burden on newly graduated nurses. Thus, it is important to improve the knowledge and skills of nurses to increase their confidence levels. Experienced nurses serve as role models for junior nurses. This study aimed to describe and analyze a project with a nursing preceptorship in an internal medicine ward in the eastern region of Sweden. Standards for Quality Improvement Reporting Excellence (SQUIRE 2.0) were used in the multi-method approach. Quality indicators, staff turnover, short-term absence, and annual survey were analyzed using descriptive statistics. Moreover, two focus group interviews were analyzed using qualitative content analysis. The results showed marginal improvements due to quality indicators and working environment, and decreased staff turnover and short-term absenteeism. Two factors, ‘supportive working environment’ and ‘improvement in nursing’, were identified. The study concluded that selection of nurse preceptors with expertise and interest in supportive and reflective approaches is significant for promoting a healthy working environment. Moreover, interventions such as nursing preceptorship facilitate implementation (<one year) and evaluation using a multi-method design to describe, explain, and understand the possible considerations and consequences of quality improvement in healthcare.