A second goal of the season for striker Petermann guided the Foxes to their second win in as many games after a crucial first-half penalty save from Janina Leitzig spurred City to take all three points from their Barclays Women's Super League meeting with the Toffees at King Power Stadium.
Willie Kirk made two changes to the side that beat Bristol City last weekend at Ashton Gate with Jutta Rantala and Josie Green coming in for Aimee Palmer and Julie Thibaud, and the attacking changes to the line-up looked to have a positive effect early on in the game.
The first chance fell to Petermann, who scored a debut goal on the opening weekend, as intense pressing from the frontline allowed the striker the chance to rob possession from the Everton 'keeper but, with her back to goal, she couldn't covert her first-time effort.
The next opening came for Rantala, another debutant to score at Ashton Gate, as she struck an effort over the bar, after some quick play with Petermann allowed some space for the Finland international just outside the Everton penalty area.
City were getting most of their fortune down the flanks with Shannon O'Brien, and Missy Goodwin in particular, who looked to have the beating of the Everton left-back in the first half, but strong defending from the Toffees cancelled out any crosses or attempted passes that made their way into the box.
The final play of the half came in favour of the visitors who were awarded a penalty in stoppage time, but as Justine Vanhaevermaet stepped up, Leitzig guessed the right way and leaped to her right-hand side to deny the Belgian, then managing to get herself up quickly to block the follow-up.
It was the visitors who came out strongest from the restart, and they managed to make the most of some spaces in between the Leicester defence to forge some openings at goal, but thankfully for City, Leitzig was well positioned to keep the Merseyside club at bay.
After a handful of substitutions from Kirk, which saw a slight change in formation, City gradually grew back into the game with confidence to drive forward and, past the hour-mark, broke the deadlock through Petermann when a brilliant interception from Sam Tierney allowed the midfielder to continue her run and slot in the German striker who finished low past Emily Ramsey.
The last 15 minutes saw several defensive reinforcements introduced into the game such as CJ Bott and Thibaud, while Canadian international Deanne Rose was brought on with the instructions to apply pressure from the front.
Under a barrage from the traveling side, there was a moment of concern for Leicester who conceded after a deflected cross was turned in by Emma Bissel - but a glance to the referee's assistant saw a raised flag, to the relief of the Foxes faithful.
Into eight added minutes and the nerves around King Power Stadium were at a high, but despite constant pressure from Everton, Leicester held on to record their first home win of the season, and continuing their impressive start to the season with six points from six.