Walsh stepped down as IAG chief executive last September, a role he held since the group – parent to British Airways – was established in 2011.
He was subsequently nominated as de Juniac’s successor in November, and formally took up the role on Thursday (1 April).
"I am grateful to Alexandre for leaving behind a strong organisation and a motivated team," said Walsh.
"Iata has been at the forefront of efforts to restart global connectivity, including developing the Iata Travel Pass.
"Together, the Iata team is absolutely focused on restoring the freedom of movement that airlines provide to billions of people around the world.
"That means your freedom to visit friends and family, to meet critical business partners, to secure and retain vital contracts, and to explore our wonderful planet."
Walsh’s career in aviation stretches back more than 40 years; he joined Aer Lingus as a cadet pilot in 1979 and went on to head up the carrier as chief executive from 2001 to 2005.
He was British Airways chief executive from 2005 to 2011 before taking the helm at the then newly-formed International Airlines Group (IAG) comprising BA, Aer Lingus and others.
Walsh served on Iata’s board of governors from 2005 to 2018, and chaired the organisation between 2016 and 2017.
‘Forceful voice’
Reflecting on the task facing Iata over the coming months and years as aviation seeks to emerge from the Covid crisis, Walsh said: “In normal times, more than four billion travellers depend on aviation each year.
"My goal is to ensure Iata is a forceful voice supporting the success of global air transport. We will work with supporters and critics alike to deliver on our commitments to an environmentally sustainable airline industry.
"It’s my job to make sure governments, which rely on the economic and social benefits our industry generates, also understand the policies we need to deliver those benefits."
