Goals from Cristian Arango and Jose Cifuentes either side of a penalty by Nashville's Hany Mukhtar put LAFC 2-1 up before prized acquisition Bale, a five-time UEFA Champions League winner, came on in the 72nd minute.
Even though LAFC were on the road, the former Real Madrid and Tottenham superstar was cheered by a sell-out crowd at Geodis Park, which included a vocal contingent of LAFC fans.
"I was itching, soon as I got on the bench I wanted to get off and help the team, play some minutes," Bale said. "Important also for me individually that I kind of get my fitness going.
"Good to get some minutes and more importantly got the three points -- yeah we're all happy."
It was Bale's first competitive club match since April 9.
Since then Bale has helped Wales earn their first World Cup berth since 1958 with a victory over Ukraine in the intercontinental playoff in June.
He signed with LAFC on June 27, two weeks after veteran Italy and Juventus defender Giorgio Chiellini announced he was moving to the club.
Chiellini also made his MLS debut on Sunday, playing the first 60 minutes.
"It was really important for us to get him and Gareth a win in their first game," LAFC coach Steve Cherundolo said.
Both Bale and Chiellini said the heat and humidity in Nashville -- a feature in many MLS venues in a regular season played in the summer months -- was something they'll have to adjust to.
"The humidity was very difficult even in the warm up," Bale said. "It's something I'm not used to.
"But these are the challenges that we all have to deal with and we have to push through and do what we have to for the team."
Chiellini said he expected his first match in nearly a month to be a physical challenge.
"But I felt better minute by minute," he said.
- Switched on -
The victory pushed LAFC ahead of Austin atop the Western Conference standings with 42 points with a game in hand over the Texas club on 41.
Cifuentes grabbed the go-ahead goal in the first minute of the second half.
LAFC's Ryan Hollingshead hit the post with a header from a pass of Carlos Vela.
Cifuentes fired home the rebound for what proved the game winner, his sixth goal of the season and his third in two matches.
Arango had scored his eighth of the season to put the visitors up 1-0 in the 27th minute.
But Mukhtar converted from the spot in the 43rd after VAR determined Ilie Sanchez pulled down C.J. Sapong in the box.
With his first MLS action under his belt, Bale said, it's now a matter of gaining familiarity with his teammates and improving his own fitness.
"It's going to take a little time to get used to everything but I'm quite switched on in terms of football so I'm able to get up to speed pretty quick.
"Now it's just important to try and get some minutes, try and get as fit as possible as quick as possible."
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)