Teesdale, who joined the agency in 1997, will leave later this month to take up the post of vice-chairman of BBDO in Atlanta, where he will lead planning on the mobile phone brand Cingular.
At AMV, he took the planning lead on BT's "It's Good to Talk" and "Bringing People Together" campaigns. He was also the co-founder of the BBDO Telco Hub and has worked with BBDO offices around the globe on telecoms accounts.
Bryant, 32, has spent the past two-and-a-half years at Mother, where he has worked on some of the agency's most high-profile accounts, including Orange, Schweppes and ITV Digital.
Before joining Mother he spent two years as a planning director for TBWA\Chiat\Day in Los Angeles after a spell with WCRS, where he held the same position.
He launched his advertising career at Lowe more than 11 years ago, working on Heineken and Weetabix.
Bryant said: "I am absolutely excited about the position. AMV is a great place with great brands and fantastic people. What impressed me was that it wants me to take my own brand of energy there and work with it rather than just playing the role of a figurehead."
The AMV group chairman, Michael Baulk, described Bryant as "immensely personable" and "infectiously enthusiastic".
He said: "If Mike's strength was strategy, then George's real power lies in his great creativity. He has the talent, the energy and the ideas to take planning forward."