Every year, the intelligence, cyber and security agency releases a card containing a festive brainteaser to national security colleagues and partners across the world.
But this year's card was packed with "fiendish puzzles" aimed at children between the ages of 11 and 18, the agency said in a statement.
Kids can work their way through an increasingly difficult set of puzzles on the Christmas tree-themed card, which is available to download.
"From Enigma to modern day encryption, GCHQ's history is full of talented people tackling the country's most complex challenges. If we're to help keep the country safe, problem-solving skills and teamwork are absolutely crucial," the agency's director, Jeremy Fleming, said in a statement.
"That's why this year's Christmas puzzles are aimed at young people. I am keen to encourage STEM skills, thinking differently, and help foster the next generation of talent.
"I want to show young people that thinking differently is a gift, and it is only with a mix of minds that they can solve seemingly impossible problems, just like we do at GCHQ," he added.
The answer to the Christmas puzzle will also be posted on Instagram and the GCHQ website, the agency said.
The agency, now based in the town of Cheltenham, is perhaps best known for its operations during World War II, when it relocated to Bletchley Park, 50 miles northwest of London.
There, code-breakers including Alan Turing famously decrypted coded German messages sent using the Enigma cipher machine.