Saturday's 5-1 victory in Madrid made the second leg virtually a formality and their goalkeeper Iker Casillas was rarely troubled in a first half they controlled.
The hosts trying to reach the finals for the first time as an independent nation were given a ray of hope five minutes into the second half when striker Filip Holosko seized on a loose ball and fired a low shot past Casillas.
David Villa calmed any Spanish nerves after 71 minutes racing on to a precise pass to fire home and extend Spain's unbeaten run under coach Luis Aragones to 18 matches.
'Now it's official we're in the World Cup. It's now down to us to work as hard as possible to prepare for next year' said Aragones who took over after Spain's flop at Euro 2004.
Captain Raul predicted that Spain would be a big threat in Germany now that they have sealed their place in the finals for the eighth time in succession.
'It's a moment to be very proud of' said the Real Madrid striker. 'Getting to the World Cup is very important to this side and I believe we have the quality to do something big when we get there.'