Mascarenhas (2/19) also shone with the ball plucking the vitil Kiwi scalps of How and Styris.
KP made most of his promotion up the order carting six boundaries and a massive six over mid-wicket while the lusty hitting Mascarenhas struck four sixes off one Jeetan Patel over as England posted a solid 184/8 in the stipulated 20 overs.
Kiwis in reply was bundled out for 152 in 19.2 overs despite Jacob Oram's (61 off 40) brave effort.
Left-armer Ryan Sidebottom was the pick of English bowlers with 3 for 16 while Anderson and Mascarenhas claimed two wickets apiece.
Earlier, Brendon McCullum stand-by captain in place of regular Vettori who is down with injury, asked the visitors to bat first.
The skipper opened well, taking an excellent diving catch to his right to dismiss Luke Wright (one) in the second over, capitalising on a deceptively quick Martin delivery.
Ryder opened his international career with a catch at deep mid-wicket off Phil Mustard (20) to give Martin his second wicket in successive overs.
Ian Bell played second fiddle to Pietersen in a third-wicket stand, adding 34 from 21 balls. But the Warwickshire man was trapped by an intelligent Oram slowish yorker for 12.
Patel came into the attack and the change was immediately significant, Ross Taylor catching Pietersen low on the onside for 43.
Rookie Ryder trapped Owais Shah (23) lbw with his second delivery.
Mascarenhas then stole the show with his onslaught, but Patel took revenge with a catch on the mid-wicket boundary off Mills
Southee accounted for the visiting captain, Paul Collingwood, for 26, Styris catching his former Durham team-mate at mid-off.
Styris was again in the action to remove Stuart Broad (six) off Mills in the penultimate over.
Ryder and McCullum opened the reply.
The skipper went for nine, including a straight six off Ryan Sidebottom before conceding his wicket to the left-arm English paceman caught by Owais Shah at square leg.
Sidebottom then doubled up two balls later to remove Ross Taylor lbw.
Jamie How sharing a stand of 28 with Ryder before giving Pietersen a regulation catch off Mascarenhas at long-on. Two balls later Ryder was caught short attempting a run.
Mascarenhas accounted for Styris (one) and Stuart Broad for Peter Fulton (eight), and the tourists took the ascendancy.
Oram took the fight to England, but ran out of partners as England went one-up in the two-match series.