"I would give him an A++. Absolutely," Sculley said during an interview on CNBC's "Fast Money."
"Tim Cook has done, I think, a terrific job of taking a company that was as much a cult as a culture and scaling it in a very complex industry."
Sculley explained that Apple continues to knock it out of the park in terms of the quality of its products. He also warned bearish traders of underestimating "the power of the iOS operating system and the loyalty of iPhone users."
The former CEO admitted that he doesn't know what the company has planned beyond its current product lines, but he's confident that Apple will "continue to have great performance for quite a few years ahead."
Investors and analysts, eyeing the Cuptertino, California-based company's cash hoard, have speculated that it may acquire another company to help boost growth.
As of its latest earnings report, Apple's cash pile sat at $231.5 billion. At the time, Howard Silverblatt, senior index analyst at S&P Dow Jones Indices, noted that if the cash hoard was its own company, it would be the 11th largest company in the S&P 500.
Sculley said that while he's not suggesting that Apple should aim for a merger or acquisition, Cook is capable of guiding the company through that process in such an event.
"I don't know whether they should, but I think Tim Cook is totally capable of running a big business," he said.