Aubameyang signed a new three-year deal last week to end months of speculation over his future, with his previous contract due to expire next summer.
The 31-year-old has hit 72 goals in 111 appearances for the Gunners, including a brace in the 2-1 FA Cup final win over Chelsea last month.
Now the Arsenal captain has committed to the club for another three years despite rumoured late interest from the likes of Barcelona.
Arteta often had to bat away questions surrounding the status of contract talks with Aubameyang but became increasingly positive the Gabon striker would stay.
However, ahead of Saturday’s Premier League visit of West Ham, Arteta conceded he was not quite as sure of Aubameyang’s future when he was appointed as Unai Emery’s successor back in December.
“To be fair at the start when I joined, I wasn’t as positive as I was in the last few weeks,” he said.
“Obviously, financially we were in a position that it was difficult to get where we wanted to get. I think Auba had his doubts as well at the time but things evolved in a natural way.
“I had the feeling that the club wanted to move forward, I had the feeling that Auba wanted to stay here and we were just trying to apply those things together and that sometimes takes time.
“But the outcome is what we both wanted so we are happy.”
While Aubameyang has stayed put, Arsenal sold goalkeeper Emiliano Martinez to Aston Villa on Wednesday.
Martinez had enjoyed a fine end to last season as he replaced the injured Bernd Leno for the closing weeks of the campaign but was dropped in favour of the Germany international for last week’s opening day win at Fulham.
Villa paid a reported £20million for Martinez as Arteta said the sale could help fund new signings.
“We have to find some balance between what we want to achieve with the squad and our finances, and it gets to a point where you have to make a decision whether to achieve certain things you have to sacrifice others,” he said.
“But time will tell whether we are weaker or not. Obviously the recruitment we are planning to do to try to get our second goalkeeper hopefully will bring us a really good performance level.”
Arteta also suggested a change in expectations from Martinez, given he had finally made it into the Arsenal side having joined 10 years ago, led to a situation where neither he nor Leno would be happy to warm the bench.
“I was very clear with both of them that it wasn’t a one and a two, they had to compete for their place like any other position in the team,” he said.
“To be fair, Bernd was superb before he got injured at Brighton and Emi was absolutely excellent with all the games he played and how much he helped us win the trophies.
“But at the end of the day that created a big competition, some big expectations from both of them and we had to deal with that.
“We were really open and trying to have those discussions, in the end Emi had a really good offer and it was very suited for what he wants to achieve long-term and short-term and we allowed him to leave the club.”
The PA news agency understands a deal to sign Dijon goalkeeper Runar Alex Runarsson is close, while Brentford’s first-choice David Raya also continues to be linked with a move to the Emirates Stadium.