Trump had urged Belarusian President Alexander Lukashenko, an ally of Russian President Vladimir Putin, to release detainees whom the US leader has described as "hostages".
Belarus later confirmed their release.
In return for Lukashenko's gesture, the US will grant sanctions relief to Belarus airline Belavia, allowing it to service and buy components for its aircraft, which includes Boeings, the US embassy said.
It was the biggest batch of prisoners pardoned by the authoritarian leader, who is seeking to repair relations with the United States after years of isolation and sanctions on his former Soviet state.
But it was far short of the 1300 or 1400 prisoners whose release Trump had called for in a conversation with Lukashenko last month and in subsequent social media posts.
Those released include Ihar Losik, 33, a journalist sentenced in 2021 to 15 years in a penal colony on charges of inciting hatred and organising riots, the Belarus affairs section of the US embassy in Vilnius said.
The embassy could not immediately confirm whether prominent critics of Lukashenko's decades-old rule, such as human rights campaigner Ales Bialiatski, co-winner of the 2022 Nobel Peace Prize, or Maria Kalesnikava, a leader of the 2020 pro-democracy protests, were among those released.
One of the 52 ex-prisoners refused to cross with the others into Lithuania, a source familiar with the matter said.
Webcam footage from the border showed a man sitting in the neutral zone between the two countries.
The Belarusian rights group Viasna said it looked like Mikola Statkevich, an opposition politician.
It was not immediately clear why he had refused to cross but the exiled opposition argues that freed political prisoners should have the right to stay in Belarus rather than submit to what it says are in effect forced deportations.
Sviatlana Tsikhanouskaya, leader of the exiled opposition whose husband Siarhei was freed from jail in June, said Thursday's release covered only four per cent of those designated as political prisoners.
"We welcome their release but, in essence, this is a trade in human lives - people who should never have been imprisoned in the first place," Tsikhanouskaya said in a statement released to Reuters in which she urged the EU to maintain sanctions on Belarus until democracy is established.
Belarus' state news agency Belta said those released included 14 foreigners - from Lithuania, Latvia, Poland, France, the United Kingdom and Germany.
Belta quoted John Coale, a lawyer who headed the US delegation to Belarus, as saying Trump had told Lukashenko that his country wanted to reopen its embassy in Minsk.
Coale had earlier passed a letter from Trump in English to Lukashenko, signed "Donald," according to footage from Belta.
The fact that Trump had signed the letter simply Donald was "a rare act of personal friendship," it quoted Coale as saying.
"If Donald insists that he is ready to take in all these released prisoners, God bless you, let's try to work out a global deal, as Mr Trump likes to say, a big deal," said Lukashenko, who praised the US leader for seeking a peace deal in Ukraine.
"Our main task is to stand with Trump and help him in his mission to establish peace," Belta later quoted Lukashenko as saying, alluding to Trump's assertion that he has resolved six or seven world conflicts.
Lukashenko has led Belarus for more than three decades.
He said as recently as August 22 that he was not prepared to release "bandits" who might "wage war" against the state.
Trump has said he plans to meet Lukashenko, long treated as a pariah by European countries, and described him as a "very respected man, strong person, strong leader".
