Cheng set a blistering pace in the third and final heat, clocking a season-best 49.89 seconds to storm into contention for the gold in Incheon, South Korea.
In what was the quickest heat of the three, Cheng beat the Philippines' Eric Shauwn Cray (50secs), Japan's Takayuki Kishimoto (50.27secs) and Kuwait's WAA Almas Jasem (50.50secs) - the quartet all qualifying for the final.
Chinese Taipei pair Yu Chia Hsuan (51.63secs) and Chen Chieh (50.11secs) were the other heat winners.
In the women's 400m hurdles, Bahrain's Oluwakemi Mujidat Adekoya is a red-hot favourite for the gold, after setting a Games record with a time of 55.09secs in the heats - shaving 0.17secs off the previous record set by China's Xueyan Leng in Hiroshima in 1994.
Elsewhere, Kuwait's Abdullah Alrashidi shone on the biggest stage, shooting all 16 of his targets in the men's skeet gold medal match.
Alrashidi missed just one of 32 targets across the semi-finals and final, beating China's Ying Xu in the decider after the latter missed three of his first six targets.
Xu did take home a gold medal with his silver though, as China edged Alrashidi's Kuwait in the men's skeet team event.
In the diving, Chinese pair Ruolin Chen and Huixia Liu took out the women's synchronised 10m platform gold medal with a score of 346.50 points.
North Korea's Kim Unhyang and Song Namhyang won silver with 320.64 points, ahead of Malaysian duo Mun Yee Leong and Pandelella Rinong Anak Pamg (313.92).
South Korea's Lee Nayoung won gold in the women's all events in the bowling, with an average of 213.83 points, edging Malaysia's Sin Li Jane (212.29).
Singapore won the women's 'team of five' gold medal, with bowlers Cherie Tan, Daphne Tan, Shayna Ng, New Hui Fen and Jazreel Tan combining to top the podium.
Abdullah Al-Sharbatly won gold for Saudi Arabia in the equestrian, clinching the jumping individual jump-off.
China won both the men's and women's cross-country mountain bike events, Zhen Wang and Qinglan Shi the respective gold medallists.
Qiang Wang added to China's gold tally in the women's singles tennis event, beating Thailand's Luksika Kumkhum in the final.