Hadjigakis was born in Trikala, Thessaly, Greece, in 1944. He is a cousin of the late Evangelos Averoff. He studied Law and Economics at the University of Athens with graduate studies in France and the U.K.
He entered politics in 1974, under the banner of the New Democracy party, and was elected to the Hellenic Parliament. He has been re-elected continually since. In 1989, he was appointed Deputy Minister of the National Economy and Minister of Labour. In 1990, he was appointed Deputy Minister of Trade and Minister of Agriculture (1991 – 1992). In March 2004, he was elected 1st Deputy Speaker of the Greek Parliament and Chairman of the Standing Committee on European Affairs. On September 2007, he became the Minister for Justice. In January 2009, he was shifted to the Ministry for Rural Development and Food.
Hatzigakis is the author of many articles, studies and books on political, social and economic topics. He has participated in many international conferences and parliamentary missions. In the past, he has been Member of the Standing Committee on Social Affairs, as well as Member of the Greek delegation to the NATO Assembly (Economic Committee).
He is married to the former Mirella Vafiadi. The couple have two sons.