The Barcelona striker netted his 52nd international goal on his landmark 100th appearance, taking full advantage of a goalkeeping error from a routine corner.
Tournament hosts Russia will also join La Celeste in the next round, with Saudi Arabia and Egypt no longer able to catch them ahead of the final round of fixtures.
Uruguay did not get going in the first half and had just a skied Edinson Cavani shot from 10 yards to show for their efforts prior to Suarez's decisive opener.
Much like in their opening-game thrashing at the hands of Russia, the Saudis were all over the place when Carlos Sanchez's corner arrived into the area, and Suarez was there to pounce once Mohammed Al-Owais failed to collect.
Cavani netted 38 times in a Paris Saint-Germain shirt last season but he was made to wait for his first goal of these finals, seeing his only shot in the opening 45 minutes blocked by Ali Al-Bulaihi.
The Green Falcons were unlucky to be behind at the midway point, having squandered a couple of good openings through Hattan Bahabri.
The Al-Shabab midfielder, one of four changes to the Saudis' starting lineup, had one strike helped over the bar by Fernando Muslera and then failed to keep a half-volley on target from closer range.
Al-Owais was making just his second competitive outing in goal for the Saudis, and the youngster never really settled after his error for Suarez's opener, parrying a deflected Suarez free kick from Uruguay's next attempt.
For the second match running La Celeste were looking disjointed, seeing manager Oscar Tabarez turn to his bench for a double change on the hour.
Cavani had a shot saved by Al-Owais in the final throes, soon after Torreira's shot cannoned off him and inches wide of the post.
The Green Falcons created far too little to warrant a point, and Mohammad Al-Sahlawi's tame shot down the middle in added time proved to be the closest they came to pulling off a shock result.
Uruguay will now face Russia in a shootout for top spot in Group A on Monday afternoon.
URUGUAY (4-4-2): Muslera; Varela, Godin, Gimenez, Caceres; C.Sanchez (Nandez 82'), Bentancur, Vecino (Torreira 59'), Rodriguez (Laxalt 59'); Suarez, Cavani
SAUDI ARABIA (4-5-1): Al-Owais; Al-Breik, Osama Hawsawi, Al Bulaihi, Al-Shahrani; Bahbir (Kanu 75'), Al-Faraj, Otayf, Al-Jassam (Al-Moghawi 44'), Al Dawsari; Al-Muwallad (Al-Sahlawi 78')