The AIM-listed firm said Dr Trevor Nichols, who has acted as chairman of the board since January 2014, will remain on the board as non-executive director.
The company, which develops Affimer biotherapeutics and reagents, said Forster brings over 25 years of experience in the pharmaceutical and biotechnology industry.
Avacta said most recently he led Immunocore as chief executive officer to become a world-leading immuno-oncology biotech, raising over £230mln in equity and non-dilutive funding as well as securing partnerships with AstraZeneca PLC (LON:AZN) and the Bill & Melinda Gates Foundation.
Alastair Smith, CEO of Avacta Group, said: “We have an exciting opportunity to build a world-leading and highly valuable biotech based on the Affimer platform.”
He added: ”Eliot's considerable experience, expertise and network will make a material difference to achieving that goal and to delivering maximum value to shareholders.”