He continued his professional career at the Rothschild Bank until he was elected to the National Assembly at age 32 in 1978.

On the request of François Mitterrand he was, at the age of 27, a candidate in the 1978 legislative election in the 2nd constituency of Lot-et-Garonne.

But it was on 19 March 1978 that he was elected for the first time as the deputy for the 3rd constituency of Landes, which moved the district to the left-wing.

For the Congress of Le Mans in November 2005, he associated himself with the New Socialist Party motion of Arnaud Montebourg, Vincent Peillon and Benoît Hamon.

Emmanuelli died on 21 March 2017 at a medical centre in Bayonne, Pyrénées-Atlantiques from complications of acute bronchitis at the age of 71.