P. Rajeev has been a member of the state committee of CPI(M) since 2005. He has served as SFI district secretary, state secretary, all India vice president, DYFI district secretary and CPI(M) Ernakulam district secretary. He was elected as Rajya Sabha MP in 2009 and later appointed as the chairman of Rajya Sabha Assurance Committee and the Panel controlling Rajya Sabha.

He has attended two councils of United Nations and addressed the UN General Assembly representing India in in 2013. He has served as CPI(M) parliamentary party deputy leader and Chief Whip in Rajya Sabha. He was the Resident Editor of Deshabhimani Daily from 2001 to 2010 and currently holds the post of Chief Editor.

He participated in World Festival of Youth and Students held in Cuba in 1997 and in South Africa in 2010. He had also won many awards for his socio-political and journalistic excellence. He had penned several books including Agolavalkaranakalathe Campus, Vivadangalile Vaividhyangal and Kazhchavattam and edited 1957 – Charithravum Varthamanavum.