In 2001, he took over control of day-to-day businesses of his father Jean-Luc Lagardère.

Today, driven by Arnaud Lagardère, the group is working to expand its business digitally, especially in publishing and media.

Arnaud Lagardère has been a Director of France Télécom (2003–2008), LVMH (2003–2009), and FIMALAC (2003–2006), and a member of the supervisory board of Le Monde (2005–2008).

According to Variety, in 2024, he has stepped down from his executive roles as he battles accusations of embezzlement in France.

Outside the group, Arnaud Lagardère was director and chairman of SOGEADE-GÉRANCE (a French holding company for aeronautics, defense, and space) from 2007 to 2013, member of the board of directors of EADS N.V. from 2003 to 2013, became chairman of EADS’ board of directors from 2012,[11] and member of the Conseil stratégique des technologies de l’information (Strategic Information Technology Council) from 2004 to 2007.