Abstract Background A comprehensive smokefree prison policy (SFPP) was introduced in Scottish prisons from November 2018, reflecting concern about inequalities in occupational exposures to second-hand smoke (SHS) and tobacco-related harms among people in custody (PiC). We aimed to address a gap, whereby few studies have sought to understand SFPP from the perspectives of people living and working in prisons. Methods As part of a comprehensive evaluation, focus groups and interviews with staff (n = 99) and interviews with PiC (n = 23) were conducted 6–9 months post-implementation of SFPP in Scotland. Data were analysed using the framework approach. Results Our study found that new restrictions on smoking had been widely accepted by PiC, after a period of adjustment which was less troublesome than participants had anticipated. Benefits of the SFPP for the safety and comfort of staff and PiC who were no longer exposed to SHS, and additionally for the health of PiC who were now smoking-abstinent, were widely acknowledged. Drawbacks of the SFPP, such as difficulties managing without tobacco and use of alternatives (e.g. e-cigarettes and changes in use of illegal drugs), were also reported. Contraband tobacco was not reported to be a major problem following prisons becoming smokefree. Conclusions The findings strengthen evidence that SFPPs can be implemented without causing major disruption and highlight the need for removal of tobacco to be underpinned by careful planning, partnership working and ensuring the availability of support for smokers. Experiences from Scotland may be of interest and some comfort, internationally for jurisdictions considering smoke-free rules in prisons.