PSU, consumer durables, infrastructure and auto stocks remained in the lead. Positive Asian shares added to optimism.
Buying by domestic institutional investors (DIIs) lifted mood too, traders said.
The 30-share Sensex climbed 138.11 points, or 0.41 per cent, to scale a new high of 33,295.33, breaching its previous intra-day record of 33,286.51 hit on October 27.
All the sectoral indices led by PSU and infrastructure were trading in positive territory, with gains of up to 0.98 per cent.
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Stock of Maruti Suzuki India, the country's largest carmaker, was trading up by 1.44 per cent as its second quarter net profit edged up.
Others that lifted the key indices to record highs are ONGC, Reliance Industries, Bharti Airtel, Tata Steel and SBI, rising by up to 2.51 per cent.
Other Asian markets saw a firming trend as investors tracked a record closing on Wall Street on Friday.
Hong Kong's Hang Seng was trading higher by 0.06 per cent while Japan's Nikkei rose 0.35 per cent. Shanghai Composite, however, shed 0.09 per cent today.