Conte was delighted with the efforts of his front three of Costa, Eden Hazard and Pedro, as they caused problems for the Boro defence while doing their fair share of defensive work in the second half.
"Diego is playing good football, with the ball and without the ball," Conte told Sky Sports. "Eden and Pedro, also - they're very important for our balance and working very hard for the team.
"He's a fantastic striker and he's showing this."
Conte continued: "It was a good performance against a very strong team. Don't forget that they drew with Arsenal and City away, so I'm pleased with the performance and the attitude of the players.
"We created many chances to score the second goal. It's important that you kill the game if you have the possibility. A corner, a cross - anything can happen.
"This is the sixth game in a row that we didn't concede and that's good news for us."
Conte was relieved to come away with maximum points ahead of a difficult two weeks for Chelsea, who host Tottenham next Saturday before a trip to Manchester City.
"It was very important not to lose a point today," he said. "Now we have five days to prepare for a game against a strong team like Tottenham. But when I see these players work in this way, I'm pleased.
"It's normal to fight for the best position of the table. After a bad season like last year, it wasn't easy. Now, it's not easy. We mustn't forget our difficult month we had one month ago."
Boro boss Aitor Karanka was frustrated with his side's defending at the corner from which Costa scored, while Chelsea's perceived time-wasting also drew his ire, but he insisted he was happy with the home side's performance at the Riverside Stadium.
"You can't be pleased when you've lost a game but I'm very pleased with the attitude of my players," he said.
"We knew we were going to play the team now top of the table so we knew it was going to be difficult and we did almost everything. Once again, we're in the Premier League and with one mistake, you're punished.
"We played against a team who have scored 16 goals in five games and today they were wasting time, asking for the time.
"We would have liked to win the game but this was the way we played against Arsenal, Man City, Bournemouth, so we have to keep going.
"Costa is one of the top scorers in the world, so when you play against players like Diego, I told them that you can't lose him for one second.
"But I don't want to say anything bad about my players today."