The man surnamed Ou, who comes from Central China's Hunan province, admitted to his role in the attack after he was arrested.
Ou, 25, was detained in Guangzhou's Baiyun district at 11:47 am Wednesday, police said.
The blast that took place on No 301 bus at about 7:40 pm Tuesday left two dead and 32 injured. The wounded were immediately sent to three nearby hospitals for treatment.
The case raised concerns in both the Guangdong provincial and Guangzhou city government.
Guangdong Party chief Hu Chunhua and governor Zhu Xiaodan urged investigation of the case to its fullest extent and make the finding public.
Chen Jianhua, mayor of Guangzhou, arrived in the hospitals to visit to victims and urged doctors to do what they can to heal the wounded.
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