Dyer came off the bench with seven minutes remaining of Saturday's 2-2 Premier League draw at Birmingham after three weeks on the sidelines.
The 31-year-old impressed at the start of the season as he aimed to get his career back on track following a succession of serious injury problems.
"Kieron is good," Hammers boss Grant told his club's official website.
"He hasn't trained a lot but he felt better. I am sure he will help us as he looked good again.
"All the games he has played this season, he has done well, but he had only trained twice before the match so we needed to manage him."
Dyer's introduction on Saturday almost saw rock-bottom West Ham seal their first Premier League away win in 23 attempts after they had earlier blown a two-goal lead.
Grant added: "I am concerned we let two goals slip but I prefer to look at the positives.
"We played good football, we scored two good goals. What I want from now on is to continue to play our football like in the last two months.
"We will turn the corner. Sometimes, when you are at the bottom of the league, you might think the mentality is not good but we are playing good football and the results will come.
"We just need to continue doing the right things."
The visitors were denied a penalty at St Andrews in the final two minutes when Lars Jacobsen appeared to be tugged back by Jean Beausejour.
Grant said: "We played the football I believe in, and had the right balance between attack and defence.
"We were dangerous, we did everything right and we were very unlucky with the decision of the referee not to give us a penalty at the end.
"It cost us another two points but we will continue to play the right way."
Denmark right-back Jacobsen, who was adamant he had been fouled on Saturday, believes it is vital West Ham take points from their two home games this week against promoted West Brom and Blackpool.
"The games are coming quick now and we have another one on Wednesday and we have to win it and keep collecting points," he said.
"When you are standing there after a very difficult away game at Birmingham and are disappointed with getting one point, I think that's a positive. Now we have to build on it and get our points at Upton Park in the next two games.
"If you look at our position and look at the way we played, it's clear we don't belong there."
Having endured two injury-affected spells with Everton and Blackburn, summer signing Jacobsen is also happy to be back to full fitness.
"I feel well in my position and I feel well in the team," he said.
"I think I have settled in quite well and I just want to build from now on. I think my performances will keep getting better and better.
"I feel like I have a little bit more to offer every time I step on the pitch so I just have to keep on working hard and hopefully we'll get some results and some points for West Ham."