MMP looks set to stay, with more than half the advance referendum votes in favour of the current electoral system.
The results are in line with recent polls, which have consistently shown a preference to retain MMP.
The referendum, held at the same time as today's election, asked voters whether or not they wanted to keep MMP, and to choose their preference of four replacement electoral systems.
With almost all the advance votes counted, some 53.8 percent of 282,743 advance voters chose to retain the system, while 42.5 percent voted for a change.
Of the alternative systems, First Past the Post received the most support, with 31.7 percent, followed by Supplementary Member on 14.4 percent, Single Transferable Vote on 11.2 percent and Preferential Voting on 8.2 percent.
More than a third of advance voters chose no alternative.
The final referendum results are due by December 10.
If more than 50 percent of people had voted to ditch MMP, Parliament would have decided whether to hold another referendum in 2014 to choose between MMP and the alternative voting system which got the most support.
But with the system seemingly safe, the Electoral Commission will conduct a review next year to consider if changes should be made to how it works. The review would be reported back to the Government by October 31.
As well as the proportionality of the system, the review will consider the more contentious aspects to MMP such as the thresholds parties must achieve to win a seat, the order of candidates on a party list, and dual candidacy.
The dual candidacy rule allows candidates to stand for an electorate and on a party list, meaning that in some cases an electorate MP can be thrown out by their local constituency but get back into Parliament on the list.
Another aspect to MMP that has drawn wide opposition is the one-seat threshold, which allows an elected electorate MP to bring in so-called "coat-tail'' MPs from their party list, even if they do not pass the 5 percent party vote threshold.
