Mfonobong Nsehe, who blogs for Forbes business magazine, says pastors own businesses from hotels to fast-food chains.
“Preaching is big business. It’s almost as profitable as the oil business,” he said.
The joint wealth of five pastors was at least $200m (£121m), he said.
Evangelical churches have grown in Nigeria in recent years, with tens of thousands of people flocking to their services.
Mr Nsehe said the richest pastor, Bishop David Oyedepo of the Living Faith World Outreach Ministry, was worth about $150m.
Bishop Oyedepo owned a publishing company, university, an elite private school, four jets and homes in London and the United States, according to Mr Nsehe.
He said three of the other richest pastors were:
Mr Nsehe said representatives of all the clergymen, except Pastor Ashimolowo, confirmed ownership of the assets he had listed on his blog.
“These pastors are flamboyant. You see them with private jets and expensive cars. This extravagance sends out the wrong message to their followers,” he told the BBC’s Network Africa programme.
He said the pastors acquired their wealth from various sources, including their congregations.
“We have Nigerians who are desperate, looking for solutions to their problems. They go to church for salvation, redemption and healing and pastors sometimes take advantage of them,” Mr Nsehe said.