Appearing in public for the first time since conceding, the Democrat said she hoped Mr Trump would be a successful president for all Americans.
The Republican will become the 45th US president after an astounding victory which followed a divisive campaign.
He holds his first transition meeting with outgoing President Barack Obama at the White House on Thursday.
Mr Trump's transition team for the 10-week period until inauguration will be led by Chris Christie, the governor of New Jersey.
The president-elect has said his immediate priorities are restoring the country's infrastructure and doubling its economic growth.
After losses overnight as Mr Trump's surprise victory became clear, markets rebounded and a feared meltdown failed to materialise.