A moment of genius from Hendrick created the 69th minute goal from Walters that secured a crucial win over Georgia at the Aviva Stadium.
Hendrick beat three defenders as he cut-in off the left wing before sliding-in a low cross that Walters managed to bundle over the line.
Afterwards, O'Neill praised the battling spirit shown by his players.
The final score at the Aviva was 1-0.
The win leaves Ireland four points clear of Scotland in the battle for third place after the Scots suffered a 3-2 loss to group leaders Germany at Hampden Park.
Also in Group D tonight, Poland boosted their goal-difference with an 8-1 win over Gibraltar.
Elsewhere, Northern Ireland are still on course to reach Euro 2016
An injury time goal in Belfast last night meant a 1-1 draw with Hungary for Michael O'Neill's team, who remain top of Group F.
England are among the teams in action tonight.
Roy Hodgson's side have already secured their place at next year's Championships as they prepare to host Switzerland tonight in Group E.
Hodgson will be without midfielder Michael Carrick tonight at Wembley after the Manchester United star was forced to withdraw from the squad through injury.
Among tonight's other games, Sweden will host run-away Group G leaders Austria while Spain and Slovakia are tied on 18 points apiece in Group C as they prepare to face Macedonia and Ukraine respectively.
All of those matches will kick-off at 19:45.
