The 54-year-old went on to label the achievement as a 'terrific team effort', which has seen the Blue Tigers win all four of their games in their qualification group and have been assured of a top-two spot.
"I have to say that we got there in the end. Our goal was to get three points and qualify for the Asia Cup. We have done that. I'm immensely proud of this team. They have taken my demands on board and the pressure I have put on them.
"They are one of the best Indian teams in the history if not the best. I also have to thank my staff - everybody have been wonderful. it's not just our success, the clubs have played their part as well and it is a collective success for the nation. I'm very proud," gushed Constantine.
However, the Englishman was quick to assert that he won't be allowing the team to slack off and ensure they win the group by winning the remaining two games against Myanmar and Kyrgyzstan, a sentiment echoed by captain Sunil Chhetri as well.
"We want to finish first in the group now. We have to ensure we don't ease off in the next games. So I can't say there will be any changes (in the coming games). There may be one or two depending on the situation of the players. That's about it," Constantine asserted.
Sunil Chhetri, who scored one of the goals, said, "We have qualified now. But our work is not done. We need to work harder because things will get difficult for us now that we are a qualified team. We will keep improving now and put our heads down and grind hard."
Constantine went on to praise the work done by Balwant Singh, whose introduction at half-time swung the game in India's favour with him supplying the assist to Chhetri's goal which restored India's lead.
"Balwant did exactly the same as he did in the last game. He scored two goals in the last game and he should have scored here too. His inclusion was great. That helped me put Sunil (Chhetri) out wide and it gave him some space as well. When Sunil gets space, he punishes teams.
"He is a great player (Chhetri) and professional. I hope he continues for some time."
India last played the Asian Cup in 2011 after winning the 2008 AFC Challenge Cup but were humbled in the group stages where they were pitted against Bahrain, South Korea and Australia. Sunil Chhetri, who was a part of that team, hoped that this win will help the country play the big teams in the continent more often.
"We played Australia, Bahrain and South Korea in 2011 and then we did not get a chance to play them. We need to play big teams like them and that is what makes this qualification special. When we reach tournaments like this, it will get us matches against big teams and later we can also invite them for friendlies.
"I just hope we continue to qualify for every edition," Chhetri expressed.
Stephen Constantine went on to highlight the progress Indian football has taken in the calendar year. "This year (2017) has been a game changer. India has hosted a World Cup and now we have secured qualification to the AFC Asian Cup. This year, the Indian Super League (ISL) runs for five months and hopefully next year, it will be longer.
"It will allow for a proper domestic schedule for the players. We are on the right track."