The Saudis started brightly in warm conditions in Barranquilla, with Fhad Almuwallad almost scoring in the opening minute but his fine run ended with a shot narrowly clearing the post.
By the 20 minute mark, Brazil were able to assert some authority on proceedings and Henrique fired on goal only for Abdullah Alsdairy to make a sure save.
Midway through came the South Americans best opening of the half, with Philippe Coutinho releasing Henrique who lost control of the ball as he tried to round the goalkeeper.
The Saudis, though, were showing some of their attacking flair seen earlier in the tournament, and Yahya Dagriri, Abdullah Otayf and Almuwallad all had a sniff of goal with none able to break the deadlock.
It was Brazil that grabbed the all-important opener just a minute after the interval. Willian displayed great technique to deflect the ball to Henrique, who advanced before slotting home. The goalscorer, however, was to depart the field just past the hour with what appeared a serious shoulder injury.
Although Saudi Arabia, through Yasir Alshahrani, spurned an excellent opening midway through the half it was Brazil controlling the contest.
The seemingly inevitable second arrived as Willian dribbled into the penalty area but, after hesitating, Gabriel Silva claimed possession and fired confidently into the back of the net.
Dudu then concluded the scoring in the late stages and, after latching onto a nice pass from defence, he fired home leaving Alsdairy with no chance.