鄧楨已婚，妻子係大律師林勁思。有兩個仔。母親鄧凌婉婷，2006年過世，享年87歲。佢妹鄧小婷，丈夫係前高等法院上訴庭副庭長、2017年香港特別行政區行政長官選舉參選人胡國興。
Deng Zhen is married, and his wife is barrister Lin Jinsi. There are two sons. Her mother, Deng Ling Wanting, passed away in 2006 at the age of 87. His sister Tang Xiaoting, whose husband is former Vice President of the Court of Appeal of the High Court and candidate for the 2017 Hong Kong S.A.R. Chief Executive Election, is Hu Kwok-hing.