"This result is legally effective from the date this document is signed," NEC chair Prach Chan was quoted as saying by local news agencies.
The remaining five seats in the country's parliament went to the royalist FUNCINPEC party, the report added.
The voter turnout stood at 84.59%, or 8.2 million people out of 9.7 million eligible voters, the report said, adding that the CPP received 6,398,311 votes, and FUNCINPEC received 716,490 votes, with 440,154 of voting papers being spoiled.
The parliamentary elections were monitored by some 604 international observers representing 61 organizations, most of them coming from Southeast Asian countries. At the elections, Cambodians were choosing from 18 parties registered, while the country’s last remaining opposition party, the Candlelight Party, was barred from the election by the Constitutional Council in May.