North Korea, who reached the quarter-finals in England in 1966, held Saudi Arabia to a 0-0 draw in Riyadh to join South Korea, Australia and Japan as the region's representatives in South Africa next year.
Third-placed pair Saudi Arabia and Bahrain also stayed in the hunt and will meet in a two-legged Asian playoff for the right to face Oceania champions New Zealand at the end of the year.
Iran and Uzbekistan bowed out after failing to get the wins they needed.
In Group One Uzbekistan lost 1-0 to Bahrain in Manama while Iran drew 1-1 with Group Two winners South Korea after conceding a late equaliser in Seoul.
North Korea had to survive a jittery finish against the Saudis after Kim Yong-jun was sent off in stoppage time in their Group Two tie.
The Saudis, bidding for their fifth successive finals appearance, play Bahrain over two legs in September with the winners advancing to a home and away playoff against New Zealand in October and November.
Bahrain only needed a draw to make the playoffs but grabbed all three points after Mahmood Abdulrahman scored from a stunning free kick in the 74th minute.
Bahrain, one of the most improved sides in Asia in recent times, then had Abdulla Marzooq sent off four minutes later but held on for victory.
Bahrain have never qualified for the World Cup finals but came close four years ago, winning the Asian playoff against Uzbekistan before being beaten by Trinidad and Tobago in an inter-confederation playoff.
Iran went ahead against South Korea through an own goal in the 51st minute from Kim Dong-jin.
However, South Korea equalised with nine minutes left thanks to Manchester United midfielder Park Ji-sung.
Tim Cahill scored twice as Australia came from behind to beat Japan 2-1 in Melbourne to finish top of Group One.
Japan's Brazilian-born defender Tulio ended Australia's seven-game streak of clean sheets with he climbed above the defence to head home in the 40th minute.
Australia drew level when Cahill struck just before the hour and went ahead when the Everton midfielder scored again in the 77th minute.
"I think it's a great statement to the rest of Asia and probably the rest of the world that you can finish a campaign like this five points ahead," Australia coach Pim Verbeek told reporters.
"We did not lose one game. We got one goal (against us). Can't have it all but I think it's fantastic and I'm very proud of the players."
