The winger is out on bail after being arrested on suspicion of sexual activity with a minor, and came off the bench in the 73rd minute on Saturday in Sunderland's 1-0 loss at Upton Park.
Some chants from West Ham supporters targeted Johnson, while the visiting fans gave the 27-year-old a warm welcome back to the pitch, but Advocaat declared it was time to move on.
"He came in on Wednesday and I spoke with him. Life goes on," the Dutch manager said.
"He did well. He's a very good player so I was happy that I could bring him in.
"That's good to know that he will be available against Newcastle."
Advocaat took charge of Sunderland for the first time on Saturday, and made a number of changes with Connor Wickham making his first league start in three games, while Lee Cattermole will return from suspension for next week's Tyne-Wear Derby against Newcastle United.
"Johnson for us is great player. Lee Cattermole is a good player, a steady player," the 67-year-old said.
"The way I saw Wickham play, I was quite pleased about it too.
"We've done something in a short amount of time.
"I took a risk with Wickham in that position, but he played brilliantly.
"That's a really positive thing."
