Wale defeated Peter Shanel Agovaka by 26 votes to 22 in a ballot of the country's members of parliament after incumbent Jeremiah Manele was ousted from power on May 7 in a no-confidence vote.
"We take government at a difficult time, given what is happening throughout the world," a visibly emotional Wale said after his election on Friday.
"We are not immune from the impacts of these geopolitical events."
Located 1600km northeast of Australia, the strategic importance of Solomon Islands has been in focus in recent years after it strengthened ties with China.
In 2022, it signed a security pact with Beijing that prompted concern from the United States and South Pacific neighbours.
Wale was highly critical of the deal, saying it would affect regional security and could jeopardise relationships with existing partners, but in recent years his approach to China has softened.
In 2025, he led a delegation to Beijing, where he praised China's economic development and said his party supported the one-China principle, according to a readout of the visit provided by China's ruling Communist Party.
On Friday, Wale told Australian public broadcaster ABC he would "look at" the China pact first and then "decide what to do with it".
Australian Prime Minister Anthony Albanese on Friday congratulated Wale in a post on X.
"I look forward to working together to continue strengthening our economic, development and security partnership," he said.
In 2024, Australia provided $A190 million package for Solomon Islands' police force, showing Canberra was its "security partner of choice", Albanese said at the time.
Australia has a longstanding security agreement with Solomon Islands.
"Matthew Wale's victory is a win for Canberra's preferred partners, but the 2022 security pact and Chinese infrastructure are going nowhere," said Connor Graham, a researcher specialising in the Pacific at Sydney-based think tank the Lowy Institute.
Wale was likely to be more open to traditional ally Australia as well as the US, but China remained critical to Solomon Islands' economy, he said.
