The worker head count for offices in the UK, Ireland and Spain fell from 556 to 508 in the last financial year, the charity's latest annual report and accounts information show.
Bosses say the outcome of the European Union membership referendum in June 2016 and the end of a five-year UK Government contract work £36.2 million were two attributing factors.
Chief executive Loretta Minghella said: "The drop in the value of the pound since the Brexit vote and the completion of our most recent Programme Partnership Agreement with the Department of International Development has meant that we have had to undertake a restructure to achieve substantial cost savings."
Taking into account individuals who work part-time or are in job share agreements, the full-time equivalent figure declined from 507 to 462.
The relief and development agency, which operates across the Americas, Africa, the Middle East and Asia, spent £884,000 on redundancy and termination payments during the year - an increase on £335k the previous year.
Among other measures taken has been a recruitment freeze.
Loretta Minghella added: "Our finances are now more resilient to the type of exchange rate shock that followed Brexit [the referendum vote] and we have secured a number of new institutional grants for programmes which commence in the current year."
Meanwhile, Christian Aid boosted its international-based staff from 402 to 423 - easing the overall headcount loss figure for 2016/17, which stood at 27.