Apple's former retail chief, Ron Johnson, told CNBC on Wednesday that the tech giant's stock is still a great bet for investors in the long run.

"I can't imagine a better buy for your portfolio for the next decade," said Johnson, founder and current CEO of Enjoy, which aims to merge online convenience with personal shopping services for tech products.

A self-professed Apple "fanboy," Johnson attributes his confidence to the company's consumer franchise, leadership, cash balance, and great products. He said he owns the stock. "I'm long. I love Apple."

However, shares of Apple, which has been in the hot seat in recent months due to slowing iPhone sales growth, is down about 12 percent over the past 12 months and off more than 30 percent since its all-time in October. In August, Apple became the first U.S. company to reach $1 trillion in stock market value. Apple's current market cap is a far cry from that at around $733 billion.

One of the factors that appears to be pressuring iPhone sales is Apple's battery replacement program. According to a well-connected Apple insider Tuesday, the company replaced 11 million iPhone batteries for $29 each during the length of offer, which started a year ago after user complaints led Apple to admit that it slowed down the performance of older devices. Apple had predicted that it would replace between just 1 million to 2 million batteries.

But Johnson pointed to a silver lining in the results of the battery program. "Those 10 million didn't upgrade their phone," he argued. "Next year, they'll be ready, right? Apple's a great buy."

Leading Apple's retail division from 2000 to 2011, Johnson designed what's considered among the best retail store strategies in the world. Before Apple, he was a Target executive for 15 years. After Apple, he served as CEO of J.C. Penney for what turned out to be a disastrous 17-months, which saw shoppers reject his radical store and pricing changes and saw investors flee the stock in droves.