The jury in Manhattan federal court deliberated for more than 12 hours over three days before reaching a verdict in a trial that had taken nine weeks.
Menendez, 70, had pleaded not guilty to the charges, which also included acting as a foreign agent and obstructing justice.
US District Judge Sidney Stein set Menendez's sentencing for October 29, a week before the November 5 election in which he is running as an independent in a bid for another six-year term in the Senate but is considered a long shot to win.
After the jury's foreperson read the verdict, Menendez rested his elbows on the table, clasped his hands together and stared straight ahead.
Shortly after the conviction, US Senate Majority Leader Chuck Schumer, a Democrat, called on Menendez to resign.
The trial centred on what federal prosecutors called several overlapping bribery schemes in which the senator and his wife Nadine Menendez accepted hundreds of thousands of dollars in cash, gold bars and car and mortgage payments from three businessmen who wanted his help.
In exchange for bribes, Menendez helped steer billions of dollars in US aid to Egypt, where one of the businessman, Wael Hana, had ties to government officials, according to prosecutors.
Menendez also was accused of seeking to influence criminal probes involving two other businessmen, Fred Daibes and Jose Uribe.
Hana and Daibes were co-defendants in the senator's trial and were also convicted on each of the counts they faced.
Uribe pleaded guilty and testified as a prosecution witness against Menendez.
Menendez previously faced corruption charges but that case ended in a 2017 mistrial in New Jersey on a narrower set of allegations.
Menendez stepped down as chair of the influential US Senate Foreign Relations Committee upon being charged last September but has resisted calls from fellow Democrats to resign.
During the trial, jurors were handed some of the gold bars that federal agents seized from the New Jersey home the senator shared with his wife.
Agents also found more than $US480,000 ($A712,600) of cash, including some stuffed in envelopes inside a jacket bearing the senator's name.
Defence lawyers argued that Menendez's advocacy for businessmen in his state was normal activity for a senator and sought to blame his wife, who prosecutors described as a go-between for bribes.
Defence lawyers noted that the gold bars were found in her closet.
They contended that the two lived largely separate lives and she kept her husband in the dark about her finances.
The defence also said that the senator for decades regularly withdrew cash from banks and stored it at his home.
His older sister testified that he picked up the habit from their parents, who fled from Cuba with cash that their father had stored in a clock.
Nadine Menendez is set to be tried separately at a later date.
She has not attended her husband's trial after being diagnosed with breast cancer.
Defence lawyers had said prosecutors failed to prove that the gold and cash found in the senator's home were bribe proceeds.
Menendez has been a fixture in Washington DC for more than three decades.
He has represented New Jersey in the Senate since 2006 after previously serving 13 years in the US House of Representatives.
Prior to that, he served in the New Jersey legislature and as a mayor.
