The Dutch sealed their place after a Robin van Persie double gave them a 2-0 win in Andorra.
Italy joined them later after coming from behind to beat the Czech Republic 2-1 in Turin with Mario Balotelli scoring the goal that sealed their berth from the penalty spot. In the same group B, Denmark won 1-0 in Armenia to move above their rivals into third place, one point shy of second.
There was also plenty for Germany, Switzerland, Russia, France, England and Bosnia to be happy about but there was gloom for Romania, Israel and Ireland plus the Czechs as their hopes either disappeared totally or became no longer feasible.
There is also some renewed belief in Iceland, who have never reached a major finals, after they beat Albania 2-1 in Reykjavik to move into second place behind Switzerland in Group E.
Bosnia, who have also yet to play in a finals, stayed top of Group G on goal difference after they won a rip-roaring game 2-1 in Slovakia and second-placed Greece beat Latvia 1-0 in Piraeus.
But the biggest cheers could be heard in Dutch and Italian towns and cities as they booked their places with two matches to spare.
The Dutch, World Cup runners up in 2010, had to wait until the 49th minute to take the lead against Andorra who have lost all eight games, scoring none and conceding 24.
Van Persie's second after a goalkeeping error means the Netherlands will take part in their 10th World Cup next year.
Qualification represents something of a redemption for Dutch coach Louis van Gaal who failed to steer the country to the 2002 World Cup in his previous stint as coach.
"We have done the job. We could not have qualified quicker for the World Cup than the way we did. We are the first from Europe," Van Gaal said.
On the match itself, he added: "We did very well. We gave our all in the first half and we made the breakthrough after the interval. That's just how we wanted it."
Germany's 3-0 win in the Faroe Islands thanks to goals from Per Mertesacker, a Mesut Ozil penalty and Thomas Mueller, means they will qualify if they beat Ireland at home in the first of their two remaining matches next month.
However, they cannot book their tickets just yet because Sweden's 1-0 win in Kazakhstan means they could still pip the Germans to top spot in Group C. Sweden's Zlatan Ibrahimovic scored after 27 seconds for their fastest goal in 101 years.
Switzerland's 2-0 win over Norway in Oslo put them five points clear of Iceland at the top of Group E but their celebrations also had to be put on hold because they can be caught if they slip up in their final two matches.
Russia also look on course for Brazil after a 3-1 win over Israel put them top of Group F, a point clear of Portugal and means they still have their fate in their hands with visits to the bottom two teams, Luxembourg and Azerbaijan, to come.
France also had a good night as their five-match run without a goal ended in a 4-2 win over Belarus although they had to come from behind twice before winning with goals by Samir Nasri, Paul Pogba and a double from Franck Ribery, including a penalty.
England escaped from Ukraine with a 0-0 draw that leaves them top of Group H with their fate in their hands and home games against Montenegro and Poland to come at Wembley.
San Marino scored their first goal of the campaign but have conceded 43 after losing 5-1 at home to Poland who kept their remote play-off chances alive behind England (16), Ukraine and Montenegro (both 15). Poland have 11 points.
Six teams have now joined Brazil in the draw for the finals with Italy and the Netherlands through along with four Asian qualifiers - Japan, Australia, Iran and South Korea.
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