Neo@OgilvyOne currently has some search capability, but Steak Media will now handle the vast majority of its paid-for-search projects for clients.
The two businesses have talked about the possibility of the WPP digital operation buying the search specialists.
Paul O'Donnell, chairman of OlgilvyOne, said: "We will see how well the partnership works and then we will look at an equity situation or an acquisition."
Neo@OgilvyOne clients include IBM, Cisco, American Express, Cancer Research UK and HBOS.
O'Donnell said that the move to work with Steak was "essentially" talent-driven.
"Just going down the recruitment approach will not give our clients what they require at the moment."
He added: "We have a good understanding of who the key players are in the area and they have a good track record. We have some people in a classic media planning and buying role, but Steak comes in as a turnkey operation."
Oliver Bishop, Steak Media co-founder, said: "They have given us the capability to become one of the largest search players around, we now have 22 people on staff and we are still recruiting."
Neo@OgilvyOne is the agency that was formed out of the separation of mOne in January. The group split into two, and MindShare Interaction was created.
The global split triggered the set up of GroupM Interaction, which will comprise MEC Interaction, Beyond (MediaCom) and Mind-Share Interaction.
In February, Steak Media landed a string of new clients, including Admiral Insurance, Elephant.co.uk, Sega, Bell Direct and Diamond Insurance.
In January, Bishop's brother Seb became chairman of Steak, taking on the position in conjunction with his role as chief marketing officer of the Miva paid-for search network.