There is increasing research interest in the experiences of new fathers taking paternity leave, but less insight into men’s experiences of returning to work after the birth of their first baby. For many men in the UK context, this could take place immediately after the birth or after one or two weeks of paternity leave. This paper utilizes data from a UK-based study whilst also drawing on international literature and policy contexts. A constructivist grounded theory method was adopted to generate theory from the data gathered. Twelve new fathers shared their experiences in this study by participating in audio-recorded, semi-structured interviews. This paper focuses on fathers’ experiences of negotiating the workplace as part of an overall theoretical framework related to broader transitions to fatherhood and sheds light on the distress, guilt and psychological challenges that the participants experienced when they initially returned to work. Whether fathers did or did not explicitly describe distress at this time, they all described a change in their worker identity, which for some participants led to uncertainty in the workplace. Men returning to work at this time in the postnatal period are vulnerable to experiencing distress. Flexibility and support in the workplace could be protective of their mental health. Finally, policy and practice developments are offered to support men’s transitions to fatherhood in the workplace context.