Kevin O'Leary, O'Shares Investments chairman and a judge on "Shark Tank," offered advice for investors looking to buy in dividend stocks in a CNBC interview on Monday.

"At the end of the day, dividends are the mother's milk of investing," O'Leary said. "If a company is using debt to maintain or grow dividends like the utilities are, simply don't buy those. Those are expensive. You could find lots of companies growing dividends from free cash flow."

O'Leary said that companies that are paying out dividends are "hitting it out of the park" with consumer numbers.

"They're delivering because 46 percent of their sales are in other markets, not just domestic. They've become really good at becoming productive and cutting costs," O'Leary said on Fast Money Halftime Report.

He said that investors can look to Europe-based companies that serve the United States.

"You can find companies that are servicing our domestic economy from Europe — GlaxoSmithKline, Roche, Nestle— and pay a discount and still get active exposure," O'Leary said.

O'Leary noted that dividends have provided 71 percent of the returns in the S&P over the last 40 years.

He said he looks forward to corporate America going back to "the old days."

"If the stock didn't pay a dividend, you couldn't get a grandmother to buy it," O'Leary said. "Maybe we're going back there, and I don't think that is a bad thing."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," which features Kevin O'Leary as a judge.