The group, which took over Will Alsop's practice just six weeks ago, has agreed to fork out £3.56 million for the firm, which was in joint 43rd place in this year's AJ100.
The deal will catapult SMC, which is headed up by Stewart McColl, into the top two places on the prestigious list. This morning's agreement represents McColl's biggest purchase to date.
And with more acquistions on the cards - McColl says he 'will definitely do more deals before the end of the year' - this AJ100 ranking is only likely to improve.
Charter, which has 120 staff and 45 architects, has had recent clients that include BT, Gillette, Trinity College Cambridge and the MoD.
Unsurprisingly, McColl said he was pleased with the deal, which will bring his staff total to 440. 'We are delighted with the acquisition of Charter, a business that was introduced to us by one of our operating companies which already held Charter in high esteem,' he said.
'We look forward to seeing our various teams collaborating with them to bring considerable benefits to our clients and our shareholders.
'We're not stopping here,' he added. 'We're constantly in talks with offices about potentially taking them over'.