Saudi Arabia defender Abdulelah Al Amri gave the Green Falcons a stunning lead in the 40th minute, reacting quickest to turn home a rebound after goalkeeper Fernando Muslera had initially kept out Mohamed Kanno's header.
Uruguay dominated possession throughout the contest, finishing the match with 67 per cent of the ball compared to Saudi Arabia's 33 per cent, according to Opta data, and registered 28 shots to the Saudis' seven.
Despite that overwhelming territorial advantage, Marcelo Bielsa's side struggled to convert their control into clear chances for long periods, with Saudi Arabia goalkeeper Mohammed Al Owais producing a string of important saves to preserve his side's lead deep into the second half.
Federico Valverde, Uruguay's captain, was among those denied by Al Owais, who got across his goal to push away a shot that appeared to be heading for the bottom corner in stoppage time.
The breakthrough finally arrived in the 80th minute when Araujo found the net to level the match and deny Saudi Arabia what would have been one of the tournament's biggest shocks.
Valverde reflected on the difficulty of the occasion after the final whistle.
"In the second half, we improved our mindset and intensity. The debut and nerves worked against us. In the second half we did what the coach asked of us and improved.
"As captain, I'm happy with everything the team gave. I want to focus on what we did to get the draw. The support from the fans gave us a lot of energy; I want to thank everyone who came. We're going to work hard to win the next match."
Saudi Arabia captain Salem Al Dawsari, who was part of the side that famously beat Argentina at the last World Cup, struck a note of disappointment despite the result against a much-fancied opponent.
"It was a good start, and I believe we deserved to win. Step by step, we can qualify for the next round. We came here to win and go as far as possible, not just to take part.
"We hope to correct our mistakes in the next match so we can secure a victory and move closer to qualification. This is not my first World Cup, and today we showed the character of the Saudi team. Unfortunately, we were not able to get the result we wanted."
Saudi Arabia have advanced beyond the group stage in just one of their six previous World Cup appearances, a record that means Al Dawsari's side will already be assessing their qualification chances carefully.
For Uruguay, the result extends a difficult opening to the tournament for South American sides, who remain without a win across two matches so far in the group stage.
Both teams now turn their attention to their second fixtures, with the draw leaving Group H finely balanced after Spain were also held by World Cup debutants Cape Verde earlier on the same day.