A spokesman for the National Election Committee told AFP Wednesday as official results were released that the ruling Cambodian People's Party (CPP) won all 125 seats up for grabs and took almost 77 percent of the vote.
Hun Sen will continue to lead the government for another five years through the triumph.
"It's like pushing a cart uphill", said independent political analyst Meas Ny. The new Government will meet for the first time a day later.
The other 19 candidates secured not more than six per cent of the votes nor managed to secure a seat in Parliament.
The dissolved opposition is planning on ramping up efforts with governments overseas to put more pressure on Hun Sen.
Mu Sochua, CNRP's vice president who lives in self-imposed exile overseas, called the new members of parliament illegitimate.
U.S. State Department spokesperson Heather Nauert said since the U.S. side has characterized the election as "flawed and neither free nor fair", the State Department is "expanding the visa restrictions initiated on December 6, 2017 on individuals involved in the undermining of democracy in Cambodia".
Nauert said Wednesday the visa sanctions would apply to people in and outside the government as well as their immediate family members in some cases.
The election committee spokesman said the ruling Cambodian People's Party received 4.8 million votes, or almost 77 percent of the total.
A complex mixed of development aid-funded road and mega-mall projects and alliances with police, army and courts have reputedly kept him in power.
General elections have been held in Cambodia every 5 years since the end of civil wars in 1993.
Hun Sen, now 66 (pictured above), defected in the 1970s from the Khmer Route regime as a commander and went on to install himself as prime minister in 1985 at the age of 32.
The message has resonated with segments of society. What I want is calm after the election, tuk-tuk (taxi) driver Nhem Ry told the news agency AFP post-election.
"We had demonstrations during previous elections which I do not like".
Western governments had pulled funding for the running of last month's vote but major creditor China maintained support. "There were no independent and credible observers and no CNRP representatives to monitor this election".
The CPP has long dominated Cambodia but the CNRP, which was founded in 2012, capitalised on discontent with corruption and inequality.
"The CPP is leading the nation to a one-party state with one man making all decisions for the entire nation through a sham election rejected by democratically elected governments", she told Reuters.
He called the July 29 election free and fair and said it was conducted according to the principle of democracy.
Twenty political parties contested in the sixth general election on July 29. The only credible opposition force, the Cambodia National Rescue Party, was disbanded past year by the courts, seen as aligned with Hun Sen, and the 19 parties that did compete in the vote were nearly all vanity vehicles or meant to give the illusion of democracy.
"But rarely to the degree and with the focused intensity".