This is also China's second Olympic tennis gold. The last time China saw gold in an Olympic tennis event was Athens 2004, where Li Ting and Sun Tiantian defeated Spain's Conchita Martinez and Virginia Ruano Pascual to win the women's doubles title, Xinhua reported.
Supported by passionate Chinese fans who made their voices heard from the opening serve, Zheng broke immediately to take a two game lead.
Zheng's serve came under heavy pressure in the third game from Vekic, but the Chinese was able to withstand the long battle of deuce to shore up a 3-0 lead.
Vekic's pressure on Zheng continued, but backed by the noisy Chinese fans, Zheng remained firm.
Zheng took the first set after breaking Vekic in the eighth game after hitting some trademark winners in 48 minutes.
More of those winners were on display in the second set as Zheng broke first to lead 2-0. But the Croatian won back two games to level the score at 2-2.
While Zheng won a point with a forehand overhead winner to lead the seventh game at 40-15, Vekic suffered a nervous breakdown, throwing her racquet to the ground and took a while to calm down again. Zheng then kept her momentum to claim the final victory without let-up.
"Since childhood, we have been instilling in her a certain kind of spirit, and that is to do this thing (play tennis). You must do it to the pinnacle of human achievement since tennis is the strong suit of Europeans and Americans, not Asians," Zheng's father said after his daughter historic victory according to South China Morning Post.