John Bridgeman, Director General of Fair Trading, said he had become "increasingly disturbed" by allegations about the pounds 840m industry, including those made in the Channel 4 Undercover Britain programme.
"The bereaved are at their most vulnerable as consumers and need protection from the effects of unfair competition and from aggressive sales techniques," he said.
The OFT said claims had been made about high prices and the alleged practice by some funeral directors of pushing consumers away from cheaper funerals towards the middle-price range where mark-ups are higher.
The inquiry will look at the structure of the funeral market, the links between funeral directors and crematoria and whether the largest companies use their market power to the detriment of consumers' interests. The average cost of a funeral is around pounds 1,200, having risen dramatically over the last few years.
The television programme showed one funeral worker using the arm of a dead woman as a "beer pump". Another threw litter into an occupied coffin. SCI, the company featured in the programme said it had already dismissed the two individuals concerned. The company said it was "shocked and saddened" by the documentary. "We will not tolerate any malpractice in our business," a spokeswoman said.
SCI is the world's largest funeral business. Based in America it moved into the UK market four years ago and now conducts 85,000 funerals a year out of a total of 600,000.
The company added that it was in favour of more effective regulation and had submitted a document to the DTI last year suggesting a single regulator. SCI resigned from the National Association of Funeral Directors last week and is joining the funeral Ombudsman scheme instead.
CWS Funeral Services, the funeral business operated by the Co-Op, said it hoped the OFT inquiry would bring national regulation. Sandy MacDonald, general manager of the group which carries out one in four of all funerals in the UK, said: "We have long been seeking regulation of the funeral sector.