Chow, 65, who is the Padang Kota assemblyperson took the oath of office before Penang Governor Ahmad Fuzi Abdul Razak at 9.35am.
The ceremony was also attended by Penang state secretary Mohd Sayuthi Bakar and state Harapan and BN leaders.
Chow, who was named as the chief minister candidate by Harapan, will lead the state government following the Harapan-BN coalition winning 29 out of the 40 seats in the Penang state legislative assembly.
He won the Padang Kota seat with a majority of 7,116 votes, securing 8,261 votes against Perikatan Nasional candidate H’ng Khoon Leng, who obtained 1,145 votes.
Chow, who is also the Batu Kawan MP, has held the Padang Kota state seat since 2008.
He was born in Kuala Lumpur on Nov 14, 1958, and attended SRJK Jalan Sungai Besi (1) before continuing his secondary education at SMJK Jalan Cochrane in 1971.
Chow then went to do his Sixth Form at Tunku Abdul Rahman College and then worked as a draftsman with a private company before continuing his studies at Universiti Sains Malaysia where he studied Social Science in 1980.
He also had a brief stint as a reporter and subsequently, as a sub-editor with the National Echo following his graduation in 1984.
Chow’s political career began when he became Lim Kit Siang’s political secretary in 1986 and then as the Penang DAP assistant secretary in 1989.
He contested for the first time in the 1990 general election and won the Pengkalan Kota state seat with a majority of 3,670 votes against BN candidate Dr Loh Hock Hun.