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.
Wickham was selected in the hole behind Jermain Defoe and Steven Fletcher, and showed enough to give Advocaat confidence he can keep Sunderland in the Premier League next season, after replacing Gus Poyet.
"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."
