The Republic of Ireland captain, who arrived last week after sealing his ?3.5million exit from Tottenham, latched on to a pass from David Beckham to open the scoring in the 2-0 victory over San Jose Earthquakes.
You're Keane: David Beckham mobs Robbie after his goal
He said: 'It couldn't have gone better for me. When you come to a new team, it's always good to get the first goal. When you go a few games without a goal, it starts to play on your mind.'
Keane, who was watched by his wide Claudine, impressed in front of the 27,000 crowd at the Home Depot Centre before being substituted to a standing ovation in the 71st minute.
The 31-year-old ws praised by Beckham, who said: 'I knew he was going to be running, and I knew where to put it.
'He's a player who knows where to run, and if you're on the same wavelength as him, you've got a real good chance. He's always going to make good runs, and it's up to us to find him.'
Eye-catching display: Claudine watched her husband in action in California
Galaxy coach Bruce Arena added: 'We're elated with Robbie. I think he had a great 70 minutes tonight, and he's going to have a lot more.
'I know Robbie's fitness isn't perhaps where he wants it to be, but he's a fit athlete. When he gets two or three games under his belt, he's going to be fine.'
According the Arena, the only drawback of Keane's debut was his somersault celebration. He joked: 'When he was younger, he used to elevate a little more.'
The victory, which was sealed by Mike Magee's late goal, increases Galaxy's lead to six points in the Western Conference.
Party time: Keane performs a cartwheel after his strike
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