Musk joined Trump in the conversation with Zelensky on Wednesday, when the Ukrainian president called the president-elect to congratulate him for his election night victory over Vice President Harris.
In the call, Musk said he would continue to support Ukraine with Starlink satellites, according to Axios. Starlink provides internet coverage.
Officially, the Trump campaign is not commenting on Musk's involvement.
“We do not comment on private meetings or conversations,” Karoline Leavitt, a spokesperson for the Trump transition, said in a statement to The Hill.
Zelensky previously described the phone call with Trump as "a productive conversation, a good conversation." He was among the first world leaders to congratulate Trump after his victory early Wednesday morning.
The Ukrainian leader also said in a Thursday speech that it was vital for allies to stand by Ukraine and to ensure any deal with Russia benefits Kyiv.
On the campaign trail, Trump has repeatedly said he would end the war in Ukraine by the time he takes office on Jan. 20, a plan that observers fear would mean giving up territory in eastern Ukraine seized by Russia since the 2022 invasion.
Trump, who met Zelensky in September, has frequently talked about his close relations with Russian President Vladimir Putin, who on Thursday also congratulated him on his electoral victory.
Musk, who is set to have some informal role in Trump's administration, has provided Starlink for Ukraine but also has been in regular contact with Putin since 2022, according to The Wall Street Journal. Musk in October 2022 said on his social platform X that he supports a peace plan generally seen as favorable to Russia.
Hungarian Prime Minister Viktor Orbán, a close ally of Trump's, predicted on Friday that the incoming U.S. president would end support for Ukraine.
"The situation on the front is obvious; there’s been a military defeat," Orban said. "The Americans are going to pull out of this war."
Kira Rudik, a Ukrainian member of parliament, said in a statement shared by the Atlantic Council think tank that with Trump poised to take office, "Ukraine must prepare a truly pragmatic and efficient victory plan."
"It is true that many Ukrainians remain concerned over Trump’s earlier statements about ending the war in a single day," Rudik said, "but we also hope that beyond the campaign trail, there is a clear understanding that wars cannot be stopped overnight without allowing dictators to have their way."