Lotinga, who is joining towards the end of the month, was a senior adviser to the Lib Dems on public services and health before joining Bell Pottinger as an account director following the 2010 General Election.
In January he took the role of MD of public affairs at Edelman and joined the agency last month, succeeding Chris Rumfitt.
At the end of January the DPM's communications role became vacant when Emma Gilpin-Jacobs resigned after just two months in the role.
The party said that Gilpin-Jacobs resigned because it became clear that the requirements of this position at this stage in the Parliament have a greater political and operational focus than the more corporate communications role that was originally envisaged, which is Emma's specialism.
Commenting on Lotinga's hiring, Clegg's special adviser James McGrory told PRWeek: "Stephen is both a lifelong supporter of the Liberal Democrats and a very experienced communications professional."
Lotinga said: "I’m delighted to be joining Nick Clegg and his talented team at such an interesting time in British politics. I’m immensely proud of what the Party has achieved in Government. This role is an enormous opportunity to communicate those achievements to the voting public."
Alex Bigg, general manager of Edelman UK, said: "Stephen is an exceptional political consultant and we’re sorry to see him go, but I totally understand that the lure of returning to a role in frontline politics was too much to resist.
"We wish him all the best and know that our loss is the Deputy Prime Minister’s gain. Edelman continues to have one of the leading public affairs practices in the country and we will be announcing shortly some exciting new additions to our team."