Mali, who have never previously qualified, were much more enterprising but failed to break down a typically tight Tunisia defence, as the hosts held onto their advantage from last Friday's first leg in Bamako.
The north Africans benefitted from a horror own goal in Mali where defender Moussa Sissako contrived to turn the ball into his own net in the first half of the first leg and then get himself sent off only four minutes later.
With a 1-0 lead, Tunisia played it safe and the return match had little of the drama of the first clash, although there was some needle between the two teams given what was at stake.
Tunisia will play at a second successive World Cup but will be among the weaker African sides, having benefitted from a fortuitous pairing in the playoffs as they avoided some of the other heavyweights.
But they again proved capable of playing on the big occasion, crowding the midfield and giving almost nothing away at the back.
It was only the second match in charge for Tunisia's new coach Jalel Kadri, appointed after the Cup of Nations finals where Tunisia fired Mondher Kebaier despite reaching the quarter-finals.
Kadri collapsed in tears at the final whistle as Tunisia celebrated with the capacity crowd at the Rades Stadium.
Mali had persuaded Everton's Abdoulaye Doucoure to switch allegiance from France and play for them in the playoffs but he was taken off at halftime of the first leg and then left out of Tuesday's starting lineup, coming on for the last 17 minutes.