In 1564, Ronneby was the location of a bloody battle during the Northern Seven Years' War between the Swedish and the Danish armies during which the Swedes under King Erik XIV besieged the city, killed many inhabitants (Ronneby Bloodbath) and burnt it to the ground.

[citation needed] Following the Treaty of Roskilde in 1658, whereby Blekinge and other southern provinces became Swedish, a navy base was built in Karlskrona – east of Ronneby – which accordingly was granted city rights, while revoking the city rights of Ronneby.

Besides the industry, it also hosted the Ronneby spa, with water believed to have healing qualities.

In the 1970s, the local diving club discovered a shipwreck off the coast of Ronneby that was eventually identified by archaeologists as Gribshunden, a 15th-century Danish warship.

The climate is very similar to neighbouring city Karlshamn, but has a somewhat higher rainfall and cooler nights throughout the year at the site located inside the premises of the local airport.