Motard enlisted in the French Navy in 1786. He was promoted to ensign in 1791, to lieutenant in 1793, and to capitaine de frégate in 1797. He then served in Brueys's general staff.
Motard helped organise the naval component of the Napoleonic Campaign in Egypt, and took part in the Battle of the Nile aboard the flagship Orient. He evacuated her before she exploded, but sustained severe injuries and was taken prisoner by the British.
After he was released, Motard served as staff officer to Ganteaume, taking part in operations in Saint Domingue.
On 8 June 1806, Sémillante captured he East Indiamen Acteon, Warren Hastings and Active. On 11 November, the encountered HMS Sceptre and HMS Cornwallis; battle broke out on 13, but the British ships had to retreat.
In December 1809, Motard was elevated to commander of the Legion of Honour. In November 1810, he was made a baron of Empire. From 4 January 1811, he headed the École spéciale de Marine in Toulon.
He retired with the rank of contre-amiral in 1814.