Trossard joined Arsenal on Friday afternoon from Brighton, arriving as part of a deal that could eventually be worth up to £26million.
Arteta is excited by the 28-year-old’s arrival and he could go straight into the squad for Sunday’s game against Manchester United.
Trossard has excelled this season for Brighton, scoring seven goals, and Arteta is hoping he can replicate that form for Arsenal.
“We are really happy to have him, he’s a player we followed for a while,” said Arteta.
“The opportunity came and we had the necessity for a player in the frontline who is versatile enough to play different positions.
“He knows the league, he has enough experience here and I think he can have an immediate impact on the team.”
Arsenal swooped for Trossard quickly after missing out on their top target Mykhailo Mudryk, who joined Chelsea last week for £88.5m.
The Gunners are currently top of the Premier League, five points clear of Manchester City and eight ahead of United in third, and Arteta wanted someone who could hit the ground running.
“[That was] very important,” said Arteta. “We have to think short-term but as well medium- and long-term.
“He gives us all that. He’s a very intelligent player. When you look at what he’s done in the last few years, he’s a player who fits our way of playing. We are happy to have him.”
Asked if the paperwork was filed before the deadline of midday on Friday, so Trossard could make his debut on Sunday at Emirates Stadium, Arteta said: “Yes I think it is, I think he’s good to go.”
Trossard trained with Arsenal for the first time on Friday and Arteta is delighted to finally have a new wide player in his squad.
The Gunners have wanted one since the summer, but they failed with an approach for Wolves’ Pedro Neto.
“In the summer we were looking for a player in that position and we weren’t able to do it,” said Arteta.
“It’s something that the squad needed. With the injuries of Gabi [Jesus] and Reiss [Nelson] we were really short in the frontline and we needed some reinforcements. We found in Leo a player who can give us what we want.”
Arsenal always do extensive background checks on new signings with Arteta determined that they fit into the club’s culture. On this occasion, that was aided by assistant coach Albert Stuivenberg who had previously coached Trossard at Genk.
“We talked about everybody that we want to recruit because character is crucial,” said Arteta. “But as well to understand how they are going to be around the club, but as well personal conversations.
“Albert did [give a good reference for Trossard]. Not [only] for now, but for the last few years as well.”