The Time Lord actor believes that Coleman, formerly of Emmerdale, gave the "most interesting" audition in front of showrunner Steven Moffat.
During an interview with BBC Radio Wales, Smith said: "[It's] very exciting news."
> Ten Things About... Jenna-Louise Coleman
> Jenna-Louise Coleman: Your first impressions - Doctor Who poll
Confirming that he has already met Coleman, Smith added: "I was part of the audition process where we met a number of wonderful actresses.
"But I think Jenna responded to Steven's writing in the most interesting way. We're very excited to welcome her to the Doctor Who family."
Coleman, who is starring in Julian Fellowes's upcoming ITV drama Titanic, is to replace Karen Gillan (Amy Pond) and Arthur Darvill (Rory Williams), who both depart midway through the next series.
> Doctor Who Steven Moffat: 'Matt Smith hasn't decided when he'll go'
> Read Jenna-Louise Coleman's Doctor Who press conference in full
Photo gallery - check out past Doctor Who companions below: