Miedema, who turns 23 this July, improved her tally in the national team to 60 after scoring in each half of the match, reports Xinhua news agency.
Cameroon once levelled the score just two minutes after Miedema's deadlock-breaker, but Dominique Bloodworth put the Oranjeleeuwinnen in front again shortly into the second half.
Despite having the ball possession advantage, the Netherlands failed to convert that into a lead until the last five minutes of the first half. Miedema raced in to head Shanice Van De Sanden's cross from the right wing in the 41st minute.
However, it merely took two minutes for Cameroon to bounce back into the duel, as Gabrielle Aboudi Onguene headed the ball past Dutch goalkeeper Sari Van Veenendaal before left-footing it into an empty net. It snapped Cameroon's scoring drought in 251 minutes at the quadrennial tournament.
Cameroon stayed in an inferior position again three minutes into the second half due to its defender's poor clearance, gifting the Dutch defender Bloodworth comfortable space to fire a close-range shot inside.
Cameroon almost found an equaliser with nine minutes from time. Onguene sped through on the right flank before sending a cutback, but substitute Henriette Akaba saw her goal-bound shot blocked by Sherida Spitse with legs.
Miedema confirmed her team's victory four minutes later, as she raced forward unchallenged before firing a shot into the net.
Bagging full points from two matches, the Netherlands secured their path to the knockout stage again following their debut at the World Cup four years ago.
( With inputs from IANS )