The pair will on Tuesday visit Port Arthur in Texas to show off a newly arrived oil tanker filled with Venezuelan crude to be processed at local refineries, according to a congressional aide and two US officials.
Trump is campaigning in the state in a bid to shore up support for Republican candidates, including US Senate contender Ken Paxton, who is locked in a tight race with Democratic candidate James Talarico.
It's not clear whether Rubio, who also serves as Trump's national security adviser, will take part in any campaign events like rallies.
But it's the first time he's hitting the road with Trump as the president barnstorms the country and his political activities have been limited since becoming secretary of state.
It's highly unusual for the nation's top diplomat to participate in political travel and the trip is the latest example of how Trump's second presidency has blurred the lines between governing and campaigning.
Attorney General Todd Blanche has already been appearing at rallies alongside Republican candidates.
The three sources who disclosed Rubio's plans before they were publicly announced did so on the condition of anonymity.
Rubio previously ran for president in 2016 and is considered a top prospect in 2028 presidential elections, but has not said whether he will run.
Weighing heavily on Republican candidates are high energy costs and voter fatigue over the US and Israel's nearly eight-month-old war with Iran — one that Trump predicted at the onset would last just weeks.
He once promised to keep the US out of foreign wars and has often labelled the Iran war a "little detour".
The conflict has spread, with Iran-backed Houthi rebels carrying out a series of attacks on Saudi Arabia's oil infrastructure and airports.
A Saudi-led coalition has responded with its own deadly attacks on Houthi-held territory in Yemen.
And over the weekend, the US State Department said it was reducing staffing at four embassies in the Middle East after receiving intelligence that Iran had stepped up efforts to target American personnel in the region and elsewhere.
Diesel prices continue to hover near all-time highs in the US, creating trouble for Republicans in typically conservative states such as Iowa, Kansas, Ohio and Texas who find themselves knotted in competitive races with Democrats.
But despite the enormous ramifications for the global economy, Trump insists the costs of war have been no big deal.
He repeatedly insists that the war's end is near, only to threaten that a new, intensive round of bombing could very well be in the offing once the election passes — often within the same campaign speech or a single exchange with reporters.
He also argues that elevated fuel prices are a temporary inconvenience worth paying to defang Iran, with its mysterious nuclear program.
"Trump's messaging on the war is resonating with a shrinking portion of the electorate," Lehigh University Opinion Observatory director Christopher Borick said.
Only a few elected Republicans have parted ways with Trump over the Iran conflict but some party strategists have been sounding the alarm for months.
Trump, for his part, has insisted that the midterm elections would have no bearing on how he approached the war.
An AP-NORC poll published last week found voters from both major political parties want the next Congress to focus on making life more affordable and end the conflict.
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