Duke and captain Luke Brattan were instrumental as the Bulls fired off three first-half goals in 34 minutes on Friday in front of national team boss Tony Popovic in the stands at Campbelltown Stadium.
It was Duke's final chance to show off his quality ahead of Australia's friendlies against Mexico and Switzerland in May and June, with Macarthur (9-7-10) finishing the A-League Men season just shy of the top six.
"I really do believe he deserves the spot," Bulls coach Mile Sterjovski said.
"He's a different profile to what the Socceroos are like.
"Whether he starts or whether he comes off the bench, I feel like he's got something different."
The seventh-placed Bulls have now missed the past two finals series, but at least sent off retiring French midfielder and two-time Melbourne Victory club champion Damien Da Silva a winner in front of a 6013-strong crowd.
Wellington also fell short of a finals berth and finished eighth (9-6-11) after eight weeks under interim coach Chris Greenacre.
The home side bamboozled Wellington for the sixth-minute opener by going short with a corner kick.
Phoenix left-back Corban Piper failed to clear Duke's cross, with veteran defender Matthew Jurman's shot deflecting off opponent Bill Tuiloma into the net.
Duke almost doubled their lead 10 minutes later off the back of a great sprint from Callum Talbot, with Wellington defender Isaac Hughes clearing the header on the line.
World Cup hopeful Duke was denied again in the 22nd minute, but Dean Bosnjak pounced on the crumbs to score.
It was Bulls skipper Brattan next on the scoresheet, with the one-cap Socceroos midfielder firing home unchallenged in the 34th minute from outside the box.
Duke finished goalless and was substituted off in the 75th minute, before teenager Henrique Olivera set up older brother Bernardo for Macarthur's fourth goal five minutes later.
The Phoenix were toothless, making just 12 shots to Macarthur's 26 as Bulls youngster Alex Robinson clinched his first clean sheet.
The 21-year-old goalkeeper held his nerve to deny 'Nix striker Ifeanyi Eze's attempts to take the lead in the league's golden boot standings.
Eze finishes with 10 goals, sandwiched between Auckland FC players Jesse Randall (nine) and leader Sam Cosgrove (11) ahead of Sunday's match against Sydney FC.
"Without finals in our grasp, we wanted to try and give Eze something to cheer about," Greenacre said.
"He'll be disappointed and hurting, but the type of character he is, he'll be really hungry to want to be better next season and wherever his future lies."
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