The 30-share index rose by 54.38 points, or 0.25 per cent, to trade at 21,087.09, supported by gains in stocks of healthcare, capital goods, power and consumer durable companies.
The Sensex had lost 68.32 points in the previous session on Tuesday. The market remained closed yesterday on account of "Christmas".
The National Stock Exchange index Nifty recovered by 11.05 points, or 0.18 per cent, to 6,279.45.
Brokers said covering-up of short positions by participants as today being the last session of current month expiry in the derivatives segment and a firming trend in the Asian region, mainly influenced the trading sentiment.
In the Asian region, Japan's Nikkei Index was up 0.91 per cent in early trade today, while Hong Kong's markets are closed today for a public holiday.