Chief operating officer Tim Carr said: 'We are obviously delighted that the tribunal unanimously ruled in favour of Waterfront.'
Sharp and Walker expressed concern about the agency's management, claiming they had had no influence at the firm.
The tribunal said it accepted that 'Mr Finney has not been very successful in his role.'
The pair are now joint MDs at six-month-old PA agency Golden Arrow Communications, whose main client is Hutchinson Ports UK. Their exits were part of an exodus from Waterfront, with six senior staffers having left over the past eight months.
Senior client manager Havard Hughes left Waterfront after five years in October and has joined Good Relations' planning and property comms team as account director.
Late last year, associate director of comms Andrew Pakes left to pursue political ambitions. Last autumn senior client manager Cameron Jones quit to join Dutch rail operator Ned Railways, while senior fiscal policy adviser Kerry McCarthy was elected Labour MP for Bristol East in May.