Arthur, making his first league start, pounced shortly after the Brakes had taken an early lead through Kaiman Anderson.
The deadlock ended ten-man Harriers’ best winning league run since September 2018.
The hosts, who had substitute Jim Kellermann sent off in the closing stages, made a couple of changes from the side which triumphed 2-0 at home to struggling Blyth Spartans the previous Saturday.
Striker Amari Morgan-Smith, available again after serving a two-match ban for being sent off in Kidderminster’s 2-1 defeat against Chester at Aggborough last month, replaced Ethan Freemantle while Arthur came in injured Omari Sterling.
The Brakes went ahead after just four minutes when Anderson rifled the ball into the roof of the net after it had rebounded to him off goalkeeper Luke Simpson following a low drive by Jack Edwards.
It was an early blow for Harriers who equalised ten minutes later through Arthur.
He confidently headed home at the back post following a pin-point cross from Sam Austin after Ashley Hemmings had unsettled the visitors’ defence with a dazzling run.
Aggborough boss Russ Penn’s troops set about trying to step up the pressure and forced a couple of corners in the space of two minutes, but both proved fruitless.
They were also awarded a free kick in a dangerous position in front of goal on the half hour mark, but Hemmings’ curling effort whistled just wide.
He also tried his luck from distance shortly afterwards, but this time his effort was safely gathered by well positioned goalkeeper Jake Weaver.
Hard working Leamington, without a league win this season, then earned a couple of quick-fire corners in the closing stages of the opening half which both proved unproductive.
The visitors started the second period on the front foot and in the first few minutes Sam Osborne had a shot hit the side-netting before Anderson saw his strong effort beaten away by Simpson.
Soon after Osborne also had a well struck free kick taken just under the bar by Simpson.
Harriers responded with a sweetly struck drive by Alex Prosser which was well pushed away for a fruitless corner by fully stretched Weaver.
At the other end an awkward free kick by Osborne almost crept into the net before the ball knocked out for a corner which came to nothing.
Leamington had a scare shortly after the hour mark when Jack Lane almost slid the ball into his own net, but a goalline clearance by Stephan Morley saved the day.
Harriers were reduced to ten men on 79 minutes when substitute Kellermann was sent off after a clash with former Aggborough campaigner Joe Clarke.
Kidderminster: Simpson; Penny, Taylor (Moyo, 62), Lowe, Richards; Austin, Montrose, Prosser, Hemmings (Maxwell, 81); Arthur (Kellermann, 68), Morgan-Smith. Subs not used: Palmer, Freemantle.
Leamington: Weaver; English, Morrison, Lane, Morley; Osborne, Clarke, Maye, Anderson (Meredith, 86); Smith (Waldron, 69), Edwards. Subs not used: Martin, Gittings, Taylor.
Referee: Ben Wyatt.