The BBC revealed in January it understood Adidas would terminate the deal as a direct result of the doping scandal sweeping the sport.
An IAAF statement on Friday said: "Our commercial relationship concludes at the end of 2016."
The original 11-year agreement started in 2008.
Sources told the BBC earlier this year it was worth, in terms of cash and product, as much as about $8m (£6.3m) per year.
Adidas said the decision was mutual and added "we would like to thank the IAAF for a successful and professional co-operation".
Adidas, the IAAF's biggest sponsor, has announced it is ending its sponsorship deal with athletics' world governing body three years early.