Sales at the iPhone giant fell 5% in the three months to December compared with the same period in 2021.
It was the biggest decline since 2019 and worse than expected.
The update came as many firms warn about a sharp economic slowdown, especially in the tech sector which boomed during the pandemic.
Apple boss Tim Cook said the firm was navigating a "challenging environment".
He blamed the sales decline on supply shortages due to Covid-19 disruption in China - where its phones are manufactured - and a strong dollar, as well as wider economic weakness stemming from rising prices, the war in Ukraine and lingering effects from the pandemic.
"As the world continues to face unprecedented circumstances ... we know Apple is not immune to it," he said on a conference call with investors.
Apple said the sales declines occurred throughout the world and hit most of its products.
Sales of its popular iPhones were down more than 8%, and sales of Mac computers dropped 29%.
The declines hit the firm's profits, which fell 13% to $30bn (£24bn).
Paolo Pescatore, analyst at PP Foresight, said the firm, like many electronics makers, is struggling to make the case that users should upgrade given "what is perceived to be incremental improvements on previous models".
"More so when everyone is tightening their belts," he added.
Globally the number of smartphones shipped sank 12% last year, according to market analysis firm Canalys.
Apple executives said they expected their services business, which includes Apple Pay and Apple News, to continue to drive growth, noting that there are now more than 2 billion active Apple devices around the world.
"When we look at the behaviour of our installed base, we think it's very promising," said chief financial officer Luca Maestri, while warning investors that the firm was expecting sales to continue to decline in the months ahead.
Other big tech companies also said they were feeling pressure in updates to investors.
Amazon, which has been struggling to re-ignite its e-commerce business, said sales at its online stores dropped 2% in the final three months of 2022, compared with a year earlier.
Overall, Amazon's sales in the three month period rose 9% to $149.2bn (£121bn), lifted by stronger growth in its cloud computing business.
But its profits dropped sharply, falling to near zero from $14.3bn (£11bn) a year ago, a change that chief financial officer Brian Olsavsky warned investors was likely to continue in coming months.
At Alphabet, parent company of Google and YouTube, sales were up just 1% in the three months to December, compared with 2021, as firms cut back on advertising - the company's main source of revenue - in the face of economic uncertainty.