Como dizer "Ele começou atuar com 10 anos" em inglês

Some more to the list, so you can build up your vocab (where we have "she" you can replace by "he"):

He began acting professionally at the age of 6.

Ashley Benson
She has been dancing competitively since she was 2 with hip hop, jazz, ballet, tap and lyrical. She has been singing since she was about 5 and she hopes to pursue that, along with her acting. Ashley started modeling at the age of 5 for dance catalogs. Ashley was then pursued by The Ford Modeling Agency at the age of 8. She worked steadily in print and is still with the Agency. At the age of 10, she wanted to pursue acting. Ashley went on to do 35 commercials, and then on to theatrical roles.
[see? Here it means that she began her acting career at the age of 6/when she was 6 - using the "journalese" lingo.]

Amber Benson was born on January 8, 1977 in Birmingham, Alabama.  ...
While still in her teens, she was involved in productions at the local community theatre. Her family moved to Los Angeles soon afterwards in 1992 so she could pursue a career in acting.
[Here not necessarily it's stated that she is young, but if you calculate, that calculation spill the beans.]
By the way, IMDb has a liking for the "pursuing career/acting...etc", they really favor this expression!

Shahidi's career began when she was only 6 years old in TV and print ads for various companies ...

Cara Delevingne - Delevingne has been modeling since she was 10 years old [modeling career then] … She started her acting career that same year with her first role in "Anna Karenina."
[same thing here, with "same year" they mean she was 10 years old when she started both careers - as a model and as an actress.]

Cameron Monaghan, 24, has been in show business since he was a toddler. Monaghan started as a child model, landing his first catalog cover when he was only five. 
[it's straightforwardly stated, so no need to comment here.]

 Dafne Keen was only 11 years old when she filmed her powerful performance in the X-Men film "Logan."

Iain Armitage, 9, went from having a theater critic blog to starring on one of the biggest TV shows of the year.
[so, he is still 9, probably he has started younger...]

Miley Cyrus grew up in the public eye. And at 25, the singer and actress has found her groove.
Cyrus became an instant teen icon with her starring role on Disney Channel's "Hannah Montana." Her acting career took off with her own movie and then the lead role in "The Last Song, " where she met her now-fiancé Liam Hemsworth. So did her singing career [… along with her rise to stardom]

Ref. thisisinsider

And no, "He started acting with 2 years Old" would be "Portuguese in English" (Portuenglish, if you wish), in the current case you would be trying to transplant the Portuguese grammar to English, it won´t work. In English we drop that "with" word.