McKinney, who was founding director of Westminster PA firm Keyturn Solutions, has joined as client services director (public affairs), reporting to MD John Preston.
McKinney said that he plans to hire PA staff 'when appropriate', as Ruder Finn aims to provide a 'more fully integrated' communications offer.
While at Keyturn, which closed last week after almost six years in business, McKinney worked on issues such as access to medicines and health technologies in cancer and HIV, plus SME regulatory issues.
Explaining the hire, Preston said: 'Straight product PR is being replaced by an increasing emphasis on policy and public participation.'
Keyturn's other two directors were Sir Irvine Patnick, who has now retired, and James Pawsey who has become a freelance consultant, McKinney said.
Prior to Keyturn, McKinney worked as a freelance public affairs consultant.