Net profit in the three quarters was up 2.2 percent from the previous year to 370.19 billion yen, including income from non-core subsidiaries.
Overall sales expanded 5.5 percent to 15.17 trillion yen, but operating profit in its core businesses fell 14.0 percent to 232.95 billion yen.
Mitsubishi's sales rose as Japan brings fossil fuel power stations back online and turns off nuclear plants amid public fears about atomic energy following the Fukushima crisis.
"This increase in consolidated operating transactions was mainly attributable to higher crude oil prices and higher transaction volumes in the energy business group," the company said in a statement.
Japan logged its annual first trade deficit for more than three decades in 2011 as surging demand for crude oil and liquefied natural gas coupled with rising prices drove up the value of imports, while exports slumped.
Japan expects to have all its 54 nuclear power stations turned off by April for scheduled inspections, and citizen opposition has so far stopped any of them resuming operations.
Mitsubishi's operating profit fell due in part to slipping sales volumes at its Australian mining subsidiary, while sales and administrative costs increased. But net profit was boosted by exchange-rate moves.
In 2010, the company had enjoyed a one-off profit boost from the sale of a mining subsidiary in Chile.
For the year to March, Mitsubishi kept its forecasts unchanged, with net profit projected to reach 450 billion yen and operating profit 360 billion yen on sales of 21.3 trillion yen.