The jobs fair was organized by New Zealand firm Working In and featured 25 companies looking for employees in countries including Chile and Germany, reported El Pais.
The venue for the event in the Madrid district of Salamanca had a capacity of 300 but the crowd who showed up was much larger.
Things got out of hand and police turned up at around 3pm to keep control of a situation where irate would-be participants were demanding back the €12 they had paid for their entry ticket.
"We feel cheated because the reality of the event didn't live up to the promise," 26-year-old Julia told El Pais.
"The room only had space for 40 people and a lot more people than that turned up."
"The whole thing was really badly organized," said 36-year-old Portuguese man Leandro.
"The company sold a whole lot more tickets than they had room for," he added.
Working In was quick to react to the problem. Although the firm had to postpone Wednesday's proceedings after just two hours, the company changed to a large venue for Thursday.
On the company website, Working In apologized for the events of Wednesday and said they would return money to anyone who asked.