Trump is the first sitting president since Ronald Reagan to address the group, which spent more than $30 million to help Trump get elected during the general election campaign.
He received the NRA’s endorsement in May, months before he accepted the Republican nomination.
Trump has already made some strides in support of firearms. He signed legislation that reversed a rule that would have required the Social Security Administration to provide information about those who are mentally ill for background checks when guns are purchased.
Gun control organizations said Trump supports the “extremist” agenda of the NRA, The New York Times reported.
Trump will be the keynote speaker at the convention Friday. Interior Secretary Ryan Zinke and Senator Ted Cruz are also expected at the convention.