The M&C Saatchi group agency won the business after a competitive pitch against EHS 4D and Elvis.
The review process, conducted by Agency Insight, started in April as National Trust looked to consolidate its fundraising, membership and loyalty activity into one shop.
MBA was the incumbent on customer acquisition programmes, while agencies that handled fundraising activity include Watson Phillips Norman, TDA and DMS.
Lida will work closely with the National Trust's creative agency, 18 Feet & Rising, which was appointed in March to develop an overarching brand strategy to widen the charity's appeal.
Maria Gara, the senior direct marketing manager at the National Trust, said: "We have ambitious plans for 2012 and have now found the partner to help us achieve this in Lida."
Mel Cruickshank, the chief executive at Lida, said: "All of the hard work and fantastic creative and strategic input by the team has paid off."