The Biancocelesti have been active on the transfer market this summer and added the strikers with international experience.
"This is an important day, as we are presenting our jewels to the public," said President Lotito at the start of pre-season training.
"We are showing the potential that can give us a different push going into the new season. We have signed Klose and Cissè, hoping they will be decisive in terms of physique, quality, character and experience.
"They can help bring Lazio back to the top level in Italy and Europe."