Primary healthcare (PHC) integration has been promoted globally as a tool for health sector reform and universal health coverage (UHC), especially in low-resource settings. However, for a range of reasons, implementation and impact remain variable. PHC integration, at its simplest, can be considered a way of delivering PHC services together that sometimes have been delivered as a series of separate or 'vertical' health programmes. Healthcare workers are known to shape the success of implementing reform interventions. Understanding healthcare worker perceptions and experiences of PHC integration can therefore provide insights into the role healthcare workers play in shaping implementation efforts and the impact of PHC integration. However, the heterogeneity of the evidence base complicates our understanding of their role in shaping the implementation, delivery, and impact of PHC integration, and the role of contextual factors influencing their responses. To map the qualitative literature on healthcare workers' perceptions and experiences of PHC integration to characterise the evidence base, with a view to better inform future syntheses on the topic. We used standard, extensive Cochrane search methods. The latest search date was 28 July 2020. We did not search for grey literature due to the many published records identified. We included studies with qualitative and mixed methods designs that reported on healthcare worker perceptions and experiences of PHC integration from any country. We excluded settings other than PHC and community-based health care, participants other than healthcare workers, and interventions broader than healthcare services. We used translation support from colleagues and Google Translate software to screen non-English records. Where translation was not feasible we categorised these records as studies awaiting classification. For data extraction, we used a customised data extraction form containing items developed using inductive and deductive approaches. We performed independent extraction in duplicate for a sample on 10% of studies allowed for sufficient agreement to be reached between review authors. We analysed extracted data quantitatively by counting the number of studies per indicator and converting these into proportions with additional qualitative descriptive information. Indicators included descriptions of study methods, country setting, intervention type, scope and strategies, implementing healthcare workers, and client target population. The review included 184 studies for analysis based on 191 included papers. Most studies were published in the last 12 years, with a sharp increase in the last five years. Studies mostly employed methods with cross-sectional qualitative design (mainly interviews and focus group discussions), and few used longitudinal or ethnographic (or both) designs. Studies covered 37 countries, with close to an even split in the proportions of high-income countries (HICs) and low- and middle-income countries (LMICs). There were gaps in the geographical spread for both HICs and LMICs and some countries were more dominant, such as the USA for HICs, South Africa for middle-income countries, and Uganda for low-income countries. Methods were mainly cross-sectional observational studies with few longitudinal studies. A minority of studies used an analytical conceptual model to guide the design, implementation, and evaluation of the integration study. The main finding was the various levels of diversity found in the evidence base on PHC integration studies that examined healthcare workers' perceptions and experiences. The review identified six different configurations of health service streams that were being integrated and these were categorised as: mental and behavioural health; HIV, tuberculosis (TB) and sexual reproductive health; maternal, women, and child health; non-communicable diseases; and two broader categories, namely general PHC services, and allied and specialised services. Within the health streams, the review mapped the scope of the interventions as full or partial integration. The review mapped the use of three different integration strategies and categorised these as horizontal integration, service expansion, and service linkage strategies. The wide range of healthcare workers who participated in the implementation of integration interventions was mapped and these included policymakers, senior managers, middle and frontline managers, clinicians, allied healthcare professionals, lay healthcare workers, and health system support staff. We mapped the range of client target populations. This scoping review provides a systematic, descriptive overview of the heterogeneity in qualitative literature on healthcare workers' perceptions and experience of PHC integration, pointing to diversity with regard to country settings; study types; client populations; healthcare worker populations; and intervention focus, scope, and strategies. It would be important for researchers and decision-makers to understand how the diversity in PHC integration intervention design, implementation, and context may influence how healthcare workers shape PHC integration impact. The classification of studies on the various dimensions (e.g. integration focus, scope, strategy, and type of healthcare workers and client populations) can help researchers to navigate the way the literature varies and for specifying potential questions for future qualitative evidence syntheses.