The students donned party harts and blew whistles to celebrate the coffee giant paying its corporation taxes and not trying to dodge them.
The stunt follows media reports in recent months accusing major companies like Starbucks, Google and Amazon of tax avoidance.
Debbie White, who was one of the organisers, said: "Tax is very important because it directly funds social services that we all rely on. By paying their corporation tax Costa are demonstrating that it is possible to be a successful business whilst being ethical. It was also a lot of fun and great for students to do some positive action."
The group was part of the Student Christian Movement, which focused on tax justice for its 2013 conference over the weekend.
Students were encouraged to lobby their universities not to sign purchasing deals with tax dodgers.
The Student Christian Movement is asking the government to push for global agreements that ensure companies contribute to the societies they operate in through taxation, both in the UK and abroad.