He joins from venture capital firm TomorrowVentures, where he held the role of chief technology strategist.
Slaby previously held the positions of technology director for the Obama presidential transition team and chief technology officer and deputy new media director to the 'Obama for America' campaign.
President and CEO Edelman, Richard Edelman said: 'By evolving our Edelman Digital business and continuing to "digitize" the broader firm, we will continue to bring digital fluency to our clients.
'Mike has pioneered stakeholder participation through digital engagement, so he is the ideal choice to lead our digital business.'
Slaby began his new role this week and will be based out of Chicago.