Dividend Kings are among the best stocks that income-seeking investors can turn to in these uncertain days. These companies have been raising their payouts for at least 50 consecutive years, which says something about the strength of their underlying businesses. And beyond the potential for the regular passive income they offer, many Dividend Kings have excellent long-term prospects, too.

Let's consider a duo of corporations in this category that investors should consider buying and holding on to for a while: Abbott Laboratories (ABT -0.69%) and AbbVie (ABBV -0.41%)

1. Abbott Laboratories

Abbott Laboratories is known as a leader in the medical devices field although it has a presence in several other areas, including nutrition and a generic pharmaceutical unit that targets primarily developing countries. The healthcare company has been highly successful thanks to its ability to develop newer and better products while delivering growing revenue and profits. 

These factors have also allowed Abbott Laboratories to sustain an impressive dividend record, with 51 consecutive years of payout raises. 

Abbott'a past is impressive, but the company's future matters more. The best part of Abbott's business remains its innovative culture. There is always a high demand for breakthrough healthcare products, something Abbott has been able to consistently deliver over the years. Here's one example of the company's innovative capabilities. 

During the early days of the pandemic, it quickly developed and marketed several coronavirus diagnostic tests and became a leader in this market. That helped Abbott keep its revenue afloat even as its medical device revenue dropped. Consider another example, namely the company's FreeStyle Libre franchise.

FreeStyle Libre is a continuous glucose monitoring (CGM) system that helps patients with diabetes track their blood glucose levels in real time throughout the day. In October, it was named the best medical technology of the past 50 years by the prominent Galien Foundation, which honors innovations in the life sciences.

The FreeStyle Libre system generated $4.3 billion in sales in 2022, an improvement of about 16% year over year. Abbott Labs expects revenue of $10 billion for this product line by 2028. We can expect Abbott to continue launching new products in this and other areas such as its structural heart and heart failure units.

The company arguably benefits from a strong moat, having acquired a solid brand name over the years while navigating the highly regulated healthcare industry. Like other consumers, physicians and patients are more likely to go back to those brands with which they are familiar. That can lead to sustained revenue, earnings, and stock price appreciation over the long run for Abbott Laboratories. 

2. AbbVie

AbbVie is a drugmaker with 51 years of consecutive dividend increases. That's not a coincidence. AbbVie was once a division of Abbott Laboratories. The two companies split in 2013, and AbbVie has delivered above-average returns since then. Although its most important product over this period, rheumatoid arthritis drug Humira, is now facing biosimilar competition, AbbVie can rely on other blockbusters to pick up the slack.

Skyrizi and Rinvoq are two immunology medicines tasked with replacing Humira. The two continue to earn new indications, many of which overlap with Humira's. Management expects combined peak revenue from Skyrizi and Rinvoq to surpass that of their predecessor eventually, which would be an impressive feat. After all, Humira is one of the most successful drugs in the history of the industry.

Beyond its immunology products, AbbVie has a deep lineup that includes cancer drugs Venclexta and Imbruvica, its Botox franchise, depression treatment Vraylar, and many more. Then there is AbbVie's equally impressive pipeline, which boasts more than 50 programs in mid- and late-stage development. Even at a 50% success rate, that's two dozen brand-new products or label expansions AbbVie can score in the next few years, at least a handful of which will meaningfully impact revenue growth for years.

In the meantime, those programs in the early stages of development will make their way through clinical and regulatory hurdles and also inch closer to approval. While losing patent exclusivity can be challenging for pharmaceutical companies, AbbVie's combination of a rich lineup, pipelines, and cycles of new approvals is precisely the remedy against patent cliffs. It's also a great recipe for long-term success on the market.

That's why investors can still trust this Dividend King to provide solid returns over the long haul.