Background <p>Healthy maternal nutrition during the postpartum period is crucial for both maternal and child health. Yet, understanding the extent and content of nutritional support from healthcare professionals (HCPs) during this period is poorly understood. We investigated current practices of postpartum nutritional counselling by HCPs, its determinants, and HCPs’ perspectives on digital nutritional counselling.</p> Methods <p>We employed a mixed-methods approach, using an explanatory sequential design involving both an online survey and elaborative semi-structured interviews based on the COM-B model. HCPs involved in postpartum care in the Netherlands were invited through social media and direct outreach via healthcare organizations.</p> Results <p>The online survey was completed by 69 HCPs. Additionally, 16 HCPs were invited for a semi-structured interview to further elaborate on their survey responses. Fifty-three HCPs (77%) provided postpartum nutritional counselling through verbal general advice (<i>n</i> = 34, 49%), referral to a dietician (<i>n</i> = 23, 33%), or referral to written information sources (<i>n</i> = 21, 30%). Determinants of nutritional counselling were available time, HCPs knowledge, and perceived clients’ characteristics and situation (e.g., culture and prior knowledge). Most HCPs (<i>n</i> = 51, 80%) championed the development of an app to support women in making healthier food choices.</p> Conclusions <p>Most HCPs offer limited postpartum nutritional counselling. To improve knowledge, HCPs would highly benefit from refresher courses on the latest dietary guidelines and the development of protocols for delivering high quality nutritional counselling. Additionally, the development of an mHealth app – introduced by the HCP - was considered a valuable addition to support HCPs with limited time.</p>