The share price rose further to US$208.38 during the day in New York before falling back a bit to close at US$207.43.
The rise in value — which means the company was worth more than Exxon Mobil, Procter & Gamble and AT&T combined — means Apple now accounts for 4% of the S&P 500.
It comes after the company announced its best June quarter results on Tuesday, beating analysts' forecasts despite a smaller than usual rise in iPhone shipments.
Apple hits $1 trillion stock market valuation - that's more than 50,000 percent of its 1980 initial public offering. Here's a look back at its history: https://t.co/rIDoygj7nG pic.twitter.com/1UfnMUTNFb— Reuters Top News (@Reuters) 2 August 2018
The revenue figure of US$53.3 billion for the quarter meant a rise of 17% on the corresponding quarter a year ago.
It was driven by higher prices for the iPhone and sales from its App Store, Apple Music and iCloud services.
Apple chief executive Tim Cook said the US$1 trillion market capitalisation was "not the most important measure” of its success but was due to focus on products, customers and company values.
In a memo to employees, seen by Reuters, Cook said it was a "significant milestone" that gave Apple "much to be proud of".
But he emphasised that it should not be the focus. "Financial returns are simply the result of Apple’s innovation, putting our products and customers first, and always staying true to our values.
"(The late) Steve (Jobs) founded Apple on the belief that the power of human creativity can solve even the biggest challenges — and that the people who are crazy enough to think they can change the world are the ones who do."
Apple was co-founded by Jobs and Steve Wozniak, with the latter being the person who provided the main technical input for the early Apple products.
“Just as Steve always did in moments like this, we should all look forward to Apple’s bright future and the great work we’ll do together," Cook added.