Ryanair Sun obtained a Polish air operator certificate in January 2018 and started operating for tour operators in the country last summer.
Buzz’s fleet of 17 aircraft will grow to 25 this summer, operating charter services and scheduled Ryanair flights.
It is one of four standalone airlines in Ryanair Group, along with Ryanair DAC, Ryanair UK and Laudamotion.
Buzz will launch its own website and app in the autumn where customers will be able to book all Ryanair Group flights.
The move revives the short-lived Buzz brand with its distinctive yellow livery, which Ryanair acquired in 2003 only to shut a year later.
Juliusz Komorek, chairman of the Buzz supervisory board, said: “We are excited to launch Buzz today [March 14], and to see our newly branded aircraft appear in Poland this autumn.
“Over the last 15 years, Ryanair has grown to become Poland’s biggest airline... and we now expect that Buzz will be Poland’s number one airline.”
Michal Kaczmarzyk, Ryanair Sun chief executive, added: “Following a successful year of growth for Ryanair Sun, we are delighted our planes will have a new and unique branding as we launch Buzz.
“Our goal is to offer services at the highest level to both customers and tour-operators.”
Low-cost carrier Buzz was set up by the UK arm of KLM in January 2000 before being sold to Ryanair for around €20 million three years later.
Ryanair relaunched it as Buzz Stansted and continued operations for a further 18 months before winding the brand down.