The South African Pistorius, who last month became the first amputee sprinter to compete in an Olympic Games, clocked 21.30 to win his heat of the 200m - T44 with effortless ease.
His crossover into non-disabled competition has made Pistorius a Paralympic icon, and he received a huge ovation from the capacity crowd at the Olympic Stadium.
'I couldn't have hoped for a better return here,' he said. 'I didn't expect to run a time like this tonight.
I couldn't have hoped for a better return here. I didn't expect to run a time like this tonight.Oscar Pistorius
'I've run my fastest time and I eased off about 20 metres from the end because I knew I was comfortable and I wanted to conserve energy for (the final) tomorrow.'
On another dazzling night of track and field action, Pistorius had to share the headlines with Irish sprint sensation Smyth.
Smyth, a training partner of USA Olympic Games ace Tyson Gay, was an equally emphatic victor as the defending champion stormed to the 100m - T13 title in 10.46, also a world record.
The reigning champion could have been competing for Great Britain such was the cheer when he was introduced to the crowd and victory was never in doubt as he won by over half a second from Cuban Luis Felipe Gutierrez.
South Africa's Jonathan Ntutu took the bronze.
Smyth only broke the world record in the heats yesterday, and he has gone even quicker in non-disabled competition.
Draped in an Irish flag which declared him the 'fastest Paralympian on the planet', he said: 'Coming in as champion, you are under pressure to retain your titles so thankfully I was able to do that.
'It was an added bonus to run quickly and break the world record again.
'To be in that stadium with 80,000 people, half of them seeming like they're Irish cheering, and even the British were really supportive, makes the whole Games a lot better.'
That silver behind Smyth was Gutierrez's second medal of the day after he led a Cuban one-two in the T13 Long Jump in the morning.
He won with 7.54m, a Paralympic record, ahead of Angel Jimenez Cabeza (7.14m). Bulgaria's Radoslav Zlatanov finished third with 6.81m.
Russian Margarita Goncharova claimed her second gold of the Games as she won the 100m - T38 to add to her Long Jump crown.
The 21-year-old clocked 13.45 to come home ahead of China's Chen Junfei and Ukraine's Inna Stryzhak.
She said: 'I hadn't expected it at all. Since 2006 I have competed with the same Ukrainian athlete (Stryzhak) and the Ukrainian always wins.'
The most loudly-greeted gold medal came from Great Britain's Richard Whitehead, the Marathon world record holder breaking his own 200m - T42 world record with a 24.38 run.
USA's Shaquille Vance was a long way behind in second and Germany's Heinrich Popow third.
Michael McKillop completed a golden night for the Irish as he beat the field to win the 800m - T37 in a world record 1:57.22, well clear of Tunsian Mohamed Charmi in second with Australian Scott Brad third.
Australia's Evan O'Hanlon broke the world record to take 100m - T38 gold, his time of 10.79 giving him victory ahead of South Africa's Dyan Buis and China's Zhou Wenjun.
Canadian wheelchair athlete Michelle Stilwell defended her 200m - T52 title, setting a Paralympic record of 33.80 in the process.
Belgium's Marieke Vervoort and USA athlete Kerry Morgan were second and third.
Ukraine's Iurii Tsaruk won gold in the 100m - T35 in 12.62, with South Africa's Teboho Mokgalagadi second and China's Fu Xinhan getting the bronze.
Russian Elena Ivanova won the 200m - T36 final, with Republic of Korea's Jeon Jae-Min taking silver and Argentinian Yanina Andrea Martinez bronze.
Cuba's Yunidis Castillo defended her 200m - T46 title with victory in a world record 24.45. Poland's Alicja Fiodorow was second, with South African Anrune Liebenberg third.
Poland's Katarzyna Piekart threw a world record 41.15m to win the Javelin - F46, with Russia's Nataliya Gudkova taking silver and Australia's Madeleine Hogan bronze.
China's Yang Liwan won the women's Shot Put - F54/55/56 ahead of 59-year-old German Marianne Buggenhagen and the USA's Angela Madsen.
Iran's Mohsen Kaedi won the Javelin - F33/34 and China's Liu Fuliang the Triple Jump - F46.
Gold medals this morning went to Tunisia's Maroua Ibrahmi in the Club Throw - F31/32/51, Iran's Jalil Bagheri Jeddi in the Shot Put - F54/55/56 and China's Zhang Liangmin in the women's Discus - F11/12.