The number of prescription opioids legally sold almost quadrupled from 1999 to 2010, despite no change in the amount of pain that Americans reported, according to the U.S. Centers for Disease Control.
Trump said his oldest brother, Fred Trump Jr., died of complications of an alcohol addiction.
"For too long, we have allowed drugs to ravage American homes, cities and towns", said Trump, who described the "very tough life" his brother led because of alcohol.
The status would mean that more resources will be available for treatment, according to NPR.
"After we review and evaluate the commission's findings, I will quickly move to implement an approximate and appropriate recommendation", Trump said.
He said the "crisis of drug use, addiction and overdose deaths, in many years" requires "all of our effort and will require us to confront the crisis in all of its very real complexity".
First Lady Melania Trump joined her husband in the East Wing to offer prayers to those fighting and recovering from drug addiction.
The president's directive will allow federal agencies to hire more public health workers.
The current budget for the Public Health Emergency Fund is $57,000.
"It's a first step, but if we're really serious about this momentum really has to build from here", said Andrew Kessler, who runs Slingshot Solutions, a consulting firm that specializes in substance abuse policy. "I'll tell you what, we've made a big impact, but still, we need the wall".
Noting it's been three months since Trump said he'd declare a national emergency, Toledo Democratic Rep. Marcy Kaptur said she hopes his administration will follow through "without delay to use this order to provide relief to the millions of families suffering from this crisis".
On March 29, President Donald Trump issued an executive order establishing the President's Commission on Combating Drug Addiction and the Opioid Crisis and vowed to lead an aggressive coordinated federal campaign against it.
The opioid commission's chairman, New Jersey Gov Chris Christie, applauded Trump's actions, saying on Twitter that Trump is "doing what we asked of him". It has developed into one of the nation's most urgent public health issues, claiming a life every 19 minutes, according to the U.S. Surgeon General.