The CQC gave the authority the lowest possible rating after an inspection in March.
Its report highlighted weaknesses in dealing with mental health and substance abuse, saying “the authority had fragmented plans to tackle these issues and need a more strategic, joined-up approach”.
The authority later said a number of key improvements had been implemented.
The Local Democracy Reporting Service quoted Smith as saying: ”It has been a privilege to serve the people of Blackpool over the last 24 years, during a period of significant change and challenge, and I have had the pleasure of working with a great group of people during that time in doing so – both internally and externally to the council.
“The pressures on Adult Social Services are many and great. Together, we have weathered some really tough times – and continue to do so – but we have also achieved many things and even in our darkest days, we must never lose sight of those and the positive differences we make to people’s lives every single day.
“I am proud to have been able to serve my community.”