The agency was founded in February last year by former NatWest PA head Amanda Jordan, along with Opinion Leader Research founders Viki Cooke and Deborah Mattinson.
Chime chairman Lord Bell said SMART would sit in a new Chime grouping alongside OLR, which Cooke and Mattinson sold to Chime for £3m in 1998.
Of the decision to buy out the agency, Bell said: 'CSR is increasingly recognised as a major opportunity for businesses to develop stronger, more committed relationships with their stakeholders.'
And on the decision to combine Smart's services with those of OLR, Bell added: 'Stakeholder consultation is such a crucial element of CSR that it makes sense to combine OLR's expertise in this area with the SMART's ability to develop and implement CSR strategy.'
SMART last year appointed former Grayling Political Strategy CEO Leighton Andrews as MD, in addition to recruiting former Burson-Marsteller consultant Des Wilson.