The 28-year-old goalkeeper has signed a four-year deal to join Aston Villa from Arsenal for a transfer fee of around £20m.
The Argentine was hailed for his displays in goal when Arsenal missed Bernd Leno due to an injury and was pivotal to the Gunners winning the FA Cup at the end of last season.
With Leno fit at the start of the new campaign, Martinez made it clear that he wanted to leave for regular football if he was overlooked, and Aston Villa managed to convince him to move to the Midlands.
Smith is delighted to add the goalkeeper to his squad and admits that he was charmed by his performances towards the end of last season
The Aston Villa boss believes Martinez is yet to hit his peak as a goalkeeper and feels that he will a long term solution for the Villans.
Smith told the club’s official site: “We are really pleased with the signing of our new goalkeeper Emiliano Martinez.
“We know how highly Arsenal rated him and we watched his outstanding performances last season in a trophy-winning top side.
“We moved for Emi when we saw the opportunity, as it is rare to be able to buy a top class goalkeeper who hasn’t yet reached their peak age and who can therefore be a key player for our club for the long term.”
Martinez is expected to make his debut when Aston Villa host Sheffield United next Monday.
