Italian news agency Ansa have reported that Cisse will join the club for €6 million and earn €2.1 million a year.
The 29-year-old forward, who was the highest goal scorer in the Greek top flight in each of his two seasons with Panathinaikos, becomes Lazio's seventh summer recruit. He will undergo a medical before signing a four year contract.
Cisse started his time at the Merseyside club well, but broke his leg in his 20th game and never managed to recapture his form when he returned from the injury. The player then returned to france with Marseille, before spending another season with England with Sunderland and moving to Panathinaikos.
Europa League hopefuls Lazio earlier agreed a deal with Lithuania defender Marius Stankevicius of Sampdoria and the club has also captured the signatures of German striker Miroslav Klose from Bayern Munich, Italian international goalkeeper Federico Marchetti from Cagliar), Albania midfielder Lorik Cana from Galatasaray, Bosnian full-back Senad Lulic from Swiss side Young Boys Bern and French-born full-back Abdoulay Konko from Genoa.