Whatever your investment style or strategy, there's no denying that tried-and true dividend stocks can be a superb addition to any portfolio. Companies with an enviable track record of paying and increasing their dividends in all types of markets can both provide a safe haven for investors in market storms while maximizing portfolio returns over the long run. 

If you're on the hunt for unstoppable dividend stocks to invest in this month, don't overlook these two powerhouses for your buy list. 

1. Eli Lilly

Eli Lilly (LLY -0.13%) has an illustrious history of maintaining and raising its payout, combined with a diverse, profitable business, which creates a compelling buying proposition for long-term investors. The stock currently yields around 1.1% based on the current share price. 

While that might seem on the low end for a dividend stock, the company has increased its payout by nearly 90% over the trailing five years alone. Meanwhile, the stock has delivered a total return of -- wait for it -- more than 370% during that same five-year period. For context, the S&P 500's trailing five-year return currently sits around 60%.  

Eli Lilly has a company history that traces all the way back to 1876. Not only is it one of the oldest pharmaceutical companies in the world, it's also one of the largest -- ranking 12th globally. The company reported revenue to the tune of $28.3 billion in 2021. That's a 15% increase from the prior year, a solid clip for such a mature business.  

Looking back at a much broader stretch of time, the pharmaceutical stock has an exceptional track record of generating steady revenue growth and profits. Over the past five-year period, Eli Lilly has grown its annual revenue and net income by respective amounts of 32% and 73%. Meanwhile, its cash from operations has grown by about 31% in that same five-year stretch.

In the most recent quarter, Eli Lilly reported revenue of $6.9 billion, a 2% increase from the prior-year period. Its net income totaled $1.5 billion, up 31% year over year. This growth continues to be driven by a wide range of the top-selling products that Eli Lilly counts as part of its portfolio, including Verzenio, a CDK inhibitor used to treat metastatic breast cancer; type 2 diabetes drugs Trulicity, Mounjaro, and Jardiance;and monoclonal antibody drug Taltz, to name a handful.  

For investors seeking a reliable dividend and consistent portfolio growth, a tried-and-true pharmaceutical stock like Eli Lilly, with its mature business and ever-expanding portfolio, could pose an intriguing buying opportunity. 

2. Johnson & Johnson 

Johnson & Johnson (JNJ -1.82%) is another dividend powerhouse to consider for your buy list this month. The company is a member of the Dividend Kings, as it has not only kept up with but increased its dividend for 60 years. To be a member of the Dividend King club, a stock must raise its dividend for at least 50 consecutive years. 

J&J's current dividend yield stands around 2.7%. For context, the average stock trading on the S&P 500 pays a dividend that yields about 2%. Moreover, Johnson & Johnson -- while not a growth stock by any means -- has delivered steady returns for investors over the years. In the past three years alone, the stock's total return comes to more than 40%.  

Historically, Johnson & Johnson's pharmaceutical and medical device segments have been its fastest growing, as well as the most prominent drivers of revenue growth and profits. In 2021, these two segments brought in combined revenues of about $79 billion. For context, the company's total 2021 revenue came to approximately $94 billion, up about 14% compared to the prior year. It also generated net income of about $21 billion, a 42% increase from 2020.  

It's no wonder then that the company has decided to spin off its consumer health business from its pharmaceutical/medical device segments into a separate, publicly traded company called Kenvue.

While the pharmaceutical/medical device company (which will retain the Johnson & Johnson name) and the new consumer health company look to be poised for different growth journeys, the latter business is nothing to sneeze at. In fact, most people know J&J for its consumer health products like Tylenol and Band-Aid.

When Kenvue launches in 2023, management has said that it expects the company to remain a leader in the consumer health space, a market on track to hit a global valuation of $425 billion this year.

Investors planning on buying and holding Johnson & Johnson for many years can benefit from the growth story of a company with an incredible track record of generating consistent business and shareholder returns.