The museum collaborated with digital agency 1000 Heads, which sent covert coded messages to selected bloggers over the past few weeks, under the pseudonym 7th Syndikate.
They met a man in a long trench coat and bowler hat at 6.45pm and followed him to an exclusive after-hours preview of the exhibition at the V&A.
It was only then that they learned the Cold War Modern exhibition was the secret that the 7th Syndikate had led them to discover.
One targeted blogger said: "I thought I'd worked out what was going on, but in the end it came as a complete surprise. I couldn't believe it when we ended up at the V&A. They really had me fooled."
The campaign was designed to entice bloggers with an interest in design to stimulate online discussions about the exhibition.
Jane Rosier, V&A's head of marketing, said: "We wanted to do something different to reach a new online audience.
"The subject of the exhibition offered us the perfect opportunity to work creatively with themes of espionage and coded communications. There has been a great online response and we hope it will lead to many new Museum visitors."
Cold War Modern: Design 1945-70 opened at the V&A on September 25 and runs until January 11 next year.