"Without him and his knowledge, formula one would fall into a giant hole," Lauda, the chairman of the Mercedes team and a triple world champion, told the Frankfurter Allgemeine Zeitung newspaper.
He said it would be "incredibly difficult" for the sport if Ecclestone, 83, is no longer able to run F1 "from one day to the next".
Given the sport's size, many insiders find it hard to believe a succession plan is not ready to be unfurled, but Lauda said: "I don't know if Bernie can be so easily replaced."
The great Austrian said the diminutive Briton has done a "perfect job" for the sport over the years.
"He made some small errors, but each of us has done that," Lauda insisted.
Even Ecclestone admits that paying the jailed former F1 banker Gerhard Gribkowsky to quieten him about his tax affairs might have been a mistake.
"I regret paying him," he told the F1 business journalist Christian Sylt.
"I should have let him write to the (British) Revenue and let them prove what he said," Ecclestone is quoted by the Express newspaper.
"It is a wonderful thing, hindsight."