It was the home side's first win in the Women's Tri-Nations series in Cromwell.
More importantly, the team showed more of the sort of form it produced to win gold at the Commonwealth Games last month.
Veteran midfielder McLaren led the way with some exhilarating breaks.
She had the ball close to her stick all night and proved a handful for the defence. She got on the scoreboard in the final quarter with a smartly taken penalty corner.
Smith was every bit as electric around the field. She injected some real energy into the attack and set up an important goal for Olivia Merry early in the third period.
Japan had a series of penalty corners but Smith broke away and knocked the ball forward for Merry, who deflected it over the goalie's stick.
The visiting side clawed a goal back through Yuri Nagai. She slammed in a deflection from a penalty corner.
The Black Sticks piled on the pressure in the third quarter but were not as clinical in front of goal as they would have hoped.
But the home side found the back net twice in the final period to finish strongly.
Smith got a well deserved goal late in the game when she deflected in from a penalty corner.
Stand-in coach Sean Dancer was pleased with the intensity on defence but felt his side could have been sharper in front of goal.
''It is great to win tonight after a couple of tough games,'' he said.
''It was pleasing to have a bit more intensity in what we are trying to do.''
The Black Sticks led 1-0 at halftime, thanks to a goal from Madison Doar. The 18-year-old has been impressive in the series so far.
She won the scramble for a deflection and clouted it past the goalie.
''I always felt one goal wouldn't be enough. The pleasing thing is we were creating opportunities, but we just needed to make a little bit more of them,'' Dancer said.
''But Japan are very good defensively and they do crowd the circle, and are pretty good in those scrappy type of situations.''
New Zealand's defensive effort was much improved. Frances Davies and Steph Dickins cut down some threatening moves but McLaren and Smith shone the most.
''You could see with Kelsey's speed and intensity that things were happening around her. And I thought Anita was exceptional tonight.
''A couple of times she took off with the ball and that is something we didn't quite have enough of in the first two games.
''That combination certainly set things up well for us.
''And real credit to the defence. We've talked a lot about it having to be better and they put in a lot of work.''
For Japan, Shihori Oikawa set up a lot of play and Hazuki Yuda made some telling touches from the back.
The Black Sticks' next assignment is against Australia tonight. Australia is undefeated with two wins, including a 4-1 victory against the Black Sticks on Sunday.
