The move, unveiled yesterday (Wednesday) at the MIPIM Property Fair in the south of France, will see the London-based practice join with the 100-strong Davis Brody Bond (DBB) firm.
While the two parties insist that the deal is not yet a full merger, both admit that it will only be a matter of time before the New York firm becomes a fully integrated part of the operation.
The development will take Aedas' global turnover to around the £70 million mark.
DBB is one of the Big Apple's most established practices and has recently found a rich vein of form.
Last year it was appointed the executive architect on the hugely contentious World Trade Center memorial, working with Michael Arad and Peter Walker, and full design architect on the memorial museum itself.
The practice, which was established in 1952, also has experience in academic buildings, having completed schemes for several Ivy League universities, including Harvard.
The agreement is the latest and clearest indication of Aedas' aggressive international growth strategy, which saw it placed fourth in last year's AJ100.
It has made no secret of its desire to take on North America, which is the biggest market in the world.
Aedas chairman James Handley told the AJ at the end of last week that the firm was also keen on DBB because it has an established office in São Paulo, giving it a foothold in the emerging South American market.
'We had a shortlist of offices in the States that we were keen to work with and we cut it back to a point where we were left with DBB,' Handley said.
'We decided that it was very compatible with us - we work in similar markets with compatible skills.
'As a firm, we are very pleased with the deal as there are not many practices which can claim to have established offices in four continents.'
Handley added that the practice was also in the process of starting up a new office in the former Soviet republic of Kazakhstan.
DBB principal Steve Davis insisted that his practice had not been forced into the deal. 'We had become increasingly interested in the way that practices should deal with the emerging global economy,' he said.
'The model that Aedas has been developing is a clever one. We like the idea of a 'necklace' of skills, staff and expertise around the world.
'We feel particularly comfortable with the philosophy that they are a global company that is operating with a local approach,' Davis added.