There is not a built in way to do this, but there are free Admin tools from the ArcGIS Marketplace that can or you can use python. Examples and more information in the link below:
You can do this using the Python API. Below is a sample:
from arcgis.gis import GIS from arcgis.gis import RoleManager import getpass import csv, time # Enter the URL to your ArcGIS Online Organization or Portal for ArcGIS portalURL = 'https://countysandbox.maps.arcgis.com' # Enter the username & password for an Administrator in your Organization username = 'jskinner_CountySandbox' password = '******' outputFile = r'C:\temp\output.csv' gis = GIS(portalURL, username, password) allUsers = gis.users.search(max_users=1000) print('Total Portal Users: ' + str(len(allUsers))) with open(outputFile, 'w') as output: dataWriter = csv.writer(output, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL, lineterminator='\n') # Write header row. dataWriter.writerow(['Full Name', 'Email', 'Username', 'Date Created', 'Role', 'Level', 'Last Login']) for user in allUsers: if user.role == 'org_admin': userRole = 'Administrator' elif user.role == 'org_publisher': userRole = 'Publisher' elif user.role == 'org_user': userRole = 'User' else: userRole = RoleManager(gis).get_role(user.role).name dataWriter.writerow([user['fullName'], user['email'], user['username'], time.strftime("%Y-%m-%d",time.gmtime(user['created']/1000)), userRole, user['level'], time.strftime("%Y-%m-%d",time.gmtime(user['lastLogin']/1000))])
Wow, everything I was trying to do an more, and to top it off it ran on the first try. This should be listed in the help docs, that I've spent hours looking through.
This, and many other "not-supported" tasks can easily be achieved in the free version of Admin Tools for ArcGIS Online. Simply use the "Export Users to CSV" tool in the Users category of tools.
If you desire, you can even filter the list many different ways, and also pick and choose which supplemental fields you can export with them, as shown below in this screenshot:
Hope this helps, good luck!
There is now an option to export a report (in .csv format) of an organization's members or of its items. It is available under Organization > Status > Reports > Create report. See details in this post: View and report status—ArcGIS Online Help | Documentation