Celestyal Nefeli (formerly MS Gemini) will replace the Celestyal Odyssey, whose charter agreement finishes at the end of October.
The company is also increasing the number of themed events on its cruises in 2016, providing more passengers with the best of Greek culture, gastronomy, history and wine.
Celestyal Nefeli can accommodate 1,074 cruisers, and was originally built in 1992 by Union Naval de Levante SA in Valencia, Spain.
The 400-cabin ship will be delivered to Celestyal in February and refurbished prior to the commencement of the 2016 cruise season.