They will be joined by their Group A rivals Scotland, and Turkey from Group D following an eventful night in qualifying.
Spain and the Scots secured spots in the top two with 15 points from six games, with Norway third on 10 points having played a game more.
Turkey thrashed Latvia 4-0 to make sure they will finish among the qualifying places.
On a chilly night in Oslo, Spain dominated possession but struggled to break down a resolute home defence, and it looked like VAR might prevent them confirming their Euro berth when Alvaro Morata had a first-half goal ruled out for offside.
The Spain striker was the centre of attention again when Gavi fired home four minutes after the break and another VAR offside check ensued.
But second time around he was in the clear and the goal was allowed to stand.
A brilliant volley from Yunus Akgun just before the hour set Turkey on course for a comprehensive win against Latvia that ensured they will take their place at next year's finals.
The visitors tried valiantly to equalise but instead they collapsed, with two late goals from Cenk Tosun and one from Kerem Akturkoglu sealing Turkey's participation in Germany.
They top their group with 16 points, six points ahead of Wales and Croatia after the Welsh beat the Croats 2-1 in Cardiff to keep their qualifying hopes alive.
Group I leaders Romania eased to a comfortable 4-0 win over Andorra while Switzerland had to come from 3-1 down to draw 3-3 at home to Belarus.
Fourth-placed Kosovo's home game against Israel, who are third in Group I on 11 points, was postponed due to the security situation in the Middle East.
Poland's hopes of qualifying from Group E suffered a blow as they came from a goal down to draw 1-1 at home to Moldova and remain third on 10 points, three adrift of leaders Albania and one behind Czech Republic, who both have a game in hand.
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