The Republican Party has won the House of Representatives after reaching the 218-seat threshold to secure the majority.
It means the party has recorded a clean sweep in the US elections, winning the presidency, the Senate, and now the House of Representatives.
There is also a conservative majority on the Supreme Court.
A House Republican victory in Arizona, alongside a win in slow-counting California earlier on Wednesday local time, gave the party the 218 House victories.
Republicans earlier gained control of the Senate from Democrats.
With hard-fought yet thin majorities, Republican leaders are envisioning a mandate to up-end the federal government and swiftly implement Trump's vision for the country.
The incoming president has promised to carry out the country's largest-ever deportation operation, extend tax breaks, punish his political enemies, seize control of the federal government's most powerful tools and reshape the US economy.
The Republican election victories ensure that Congress will be onboard for that agenda, and Democrats will be almost powerless to check it.
The past two years of Republican House control were defined by infighting as hardline conservative factions sought to gain influence and power by openly defying their party leadership.
While House Speaker Mike Johnson — at times with Trump's help — largely tamed open rebellions against his leadership, the right wing of the party is ascendant and ambitious on the heels of Trump's election victory.
The Republican majority also depends on a small group of politicians who won tough elections by running as moderates.
It remains to be seen whether they will stay on board for some of the most extreme proposals championed by Trump and his allies.
AP
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