The Lost in the Sun actor was dressed in a black sports shirt and casual grey pants on the cool day. Axl was full of energy sipping his blue bottle and he had fun carrying a large branch around.
Duhamel has taken over parenting duties while his wife singer Fergie is in Paris, France.
On Thursday afternoon, shared a shot of herself enjoying a shopping day in the city.
The couple tied the knot in 2009. They welcomed Axl in August 2013.
Image Credit: Fame/Flynet