Northern Ireland needed just a point at Stade de Luxembourg to win Group C3 but looked on course to pick up an impressive away win after establishing a 2-0 lead through Isaac Price and Bradley.
Two goals in three minutes from Seid Korac and Gerson Rodrigues drew Luxembourg level, but NI held on to secure promotion.
Despite his delight at topping the group, Bradley conceded that the game will be a “massive learning curve” for the young side after letting a two-goal lead slip.
“I thought we probably should have won the game but it’s nice to top the group and get promotion to League B, so I’m really happy,” added the Liverpool defender, who captained Northern Ireland in October’s Nations League games against Belarus and Bulgaria.
“They aren’t a bad side and they play some really good football. I think we did well to hold our nerve and see out the game when it went to 2-2. I’m sure we will learn from it.”
The draw to determine who Northern Ireland will face in World Cup qualifying takes place on Friday 13 December and Bradley feels his side are more than ready to compete.
“We’re looking forward to it, the World Cup qualifiers are starting so we’re really excited.
“We’re starting to gel as a team and we’re playing good football, so hopefully we can do well.”