“Josh has played a few games and is ready to play,” Alonso said ahead of the visit of Bournemouth.
“I saw he did well with the Under-21s; I know he didn't play the last game but he has done well.
“He has taken a step forward. He is playing more maturely and more aggressively, and is knowing what it takes to compete in the Premier League.”
Acheampong has already made six appearances for Chelsea this season and has continued to develop with England Under-21s, helping the Young Lions secure qualification for next year's European Under-21 Championship with a game to spare.
Alonso believes the defender's progress is evident and expects him to receive further opportunities.
“He is on that journey as he has great potential and great qualities,” the Chelsea manager said. “He has played and he will play again.”
The 20-year-old's ability to handle the demands of senior football has strengthened his case for a continued role in the first team. Alonso's comments also underline the importance he places on developing players who have come through Chelsea's academy.
Estevao is another young player the manager expects to feature more prominently. The Brazilian winger played in all three of his country's senior friendlies during the international break, scoring and assisting in a 4-0 victory over India.
Alonso has been managing the 19-year-old carefully after a hamstring injury disrupted the end of last season and ruled him out of the summer's FIFA World Cup.
“It's still early in the season, just a few games since we started,” Alonso said. “Este is feeling much better from the injury; we have seen with Brazil that he has played more.
“The context is different when he played with the international team than in the Premier League. We know the demands of the Premier League and we know how important Este can be in some games.
“He will have his moments and more minutes.”
Alonso's approach reflects the need to balance the winger's potential with the physical and competitive demands of English football. His international appearances offered encouraging signs of progress, but the Chelsea manager is focused on ensuring that development continues at club level.
Neither youngster is being presented as a finished product. Instead, Alonso sees both as players capable of making further contributions as they gain experience.
Acheampong has already shown that he can handle first-team responsibility, while Estevao is expected to build his involvement as his fitness improves.
With Chelsea preparing to face Bournemouth at Stamford Bridge, Alonso has made clear that both players remain part of his plans. His message is straightforward: Acheampong has earned further chances, and Estevao's opportunities should increase as the campaign unfolds.