Shehbaz Sharif was sworn-in on Monday after former Premier Imran Khan was ousted in a no-confidence vote he attempted to thwart. Khan had maintained he was the victim of a US plot that sought his removal.
White House spokeswoman Jen Psaki continued to maintain, however, that Washington does not "support one political party over another."
"We value our long standing cooperation with Pakistan, have always viewed a prosperous and democratic Pakistan as critical to US interests," she said. "That remains unchanged regardless of who leadership is."
Sharif, the younger brother of three-time former Prime Minister Nawaz Sharif, and a joint candidate of the combined opposition, secured 174 votes in Pakistan's 342-member lower legislative chamber, the National Assembly.
A minimum of 172 votes were required for a simple majority in the parliament.
Sharif's opponent, former Foreign Minister Shah Mahmood Qureshi, who was the candidate of the ousted premier's Pakistan Tehreek-e-Insaf (PTI) party, boycotted the elections following his party's decision to resign from the parliament.
Sharif has called for improving ties with the US, terming them "critical" for Pakistan, a noticeable departure from Khan’s frosty relations with Washington.
Khan, for his part, has announced that he would not accept the "imported government," calling on his supporters to protest against the new regime. Tens of thousands of his supporters took to the streets on Sunday night across the country to protest against Khan's ouster, terming it a "foreign conspiracy."