There were about 2500 concert-goers, with all the men frisked prior to entry.
“The organisers contacted us due to a possible threat scenario based on evaluating social media platforms,” a police spokesman told German news agency DPA.
“When it comes to things like that, we cannot simply stand by.”
The concert went ahead “without any disturbance”.
Minogue, who is dating Paul Solomons, seemed unfazed, taking to social media saying, “Thank you #COLOGNE!!!
Aussies will get to see the 50-year-old pop princess next year with her tour heading to Sydney’s ICC Theatre on March 5 and then to Adelaide Entertainment Centre on March 11 and the Sidney Myer Music Bowl in Melbourne on March 13.