Republicans have ditched a plan to gut the independent body that investigates political misconduct after a backlash.
The lawmakers' surprise vote to strip the Office of Congressional Ethics of its independence prompted public uproar and a dressing down from Donald Trump.
"Focus on tax reform, healthcare and so many other things of far greater importance!" the president-elect said.
The secretive move, which overshadowed the first day of the 115th Congress, was reversed in an emergency meeting.
The ethics committee was set up in 2008 following a slew of scandals that resulted in several House lawmakers being jailed.
Mr Trump made cleaning up corruption in Washington a key theme of his campaign, and he ended his tweet with "#DTS", an acronym for "drain the swamp".
Republican Speaker of the House Paul Ryan had argued unsuccessfully against the rule change, which was adopted on Monday night in a closed-door meeting, but he defended the proposal on Tuesday.
A win for Trump - Anthony Zurcher, BBC News, Washington
Donald Trump's tweets have teeth. The president-elect took to social media to express his displeasure with the move and within hours those legislative efforts were abandoned.
The independent ethics investigators had been a source of discomfort for members of Congress on both sides of the aisle, and there was significant interest in limiting their ability to conduct inquiries.
Even after Mr Trump's tweets, many congressional Republicans appeared reluctant to back down. House Speaker Paul Ryan, an initial opponent of the measure, issued a statement defending the change.
That ended up being little comfort to the party rank and file, however, as pressure increased for them to bend to Mr Trump's political will. In his first confrontation with congressional leadership, the president-elect displayed his dominance.
Mr Trump now has a valuable talking point when discussions inevitably turn back to his own ethical questions, such as how he will handle potential conflicts of interest involving his sprawling business empire.
He has made it a bit easier, at least for now, to claim he's standing behind his drain-the-Washington-swamp campaign rhetoric.
"I want to make clear that this House will hold its members to the highest ethical standards and the Office will continue to operate independently to provide public accountability to Congress," he said.
Democrats, led by Minority Leader Nancy Pelosi, lambasted the Republicans.
"Republicans claim they want to 'drain the swamp', but the night before the new Congress gets sworn in, the House GOP has eliminated the only independent ethics oversight of their actions," she said.
"Evidently, ethics are the first casualty of the new Republican Congress."
As the news spread, internet searches for "who is my representative" rocketed, according to Google Trends.
House Republicans called an emergency meeting and abruptly voted to undo the change.
Republican Senator Lindsey Graham took a shot at his party colleagues' decision to neuter the ethics watchdog, telling Fox News radio it was "the dumbest fricking thing I've ever heard".
Under the change:
- The watchdog would have no longer been independent
- Lawmakers would have voted to determine if a fellow member of Congress had broken the law
- The body would have been prevented from receiving anonymous tips
- Accusations against lawmakers would not have been made public, as they are currently
Mr Ryan - who was re-elected by fellow lawmakers on Tuesday as House Speaker - had urged his party to seek bipartisan support and to wait to push for the change later.
But Virginia Congressman Bob Goodlatte went ahead anyway and submitted the proposal.
The Republican faced scathing criticism on Twitter after he posted an op-ed he wrote arguing that the rule change would strengthen the ethics watchdog.
"That simply isn't true," one user tweeted in reply. "Your disingenuousness is jaw-dropping. Shame on you."
Another posted: "You, sir, are a LIAR. Why did you meet in secret in the middle of the night?"
"You are a traitor to the Constitution you swore to uphold," yet another tweeted.
Mr Trump's remarks about the ethics committee came on a busy day for the president-elect's Twitter account.
He also announced his first news conference as president-elect next week and said an intelligence briefing he was due to receive "on so-called 'Russian hacking'" had been delayed until Friday.
"Very strange!" he added, in his latest remarks appearing to question US intelligence assessments that the Kremlin sanctioned cyber-attacks during the US election season.