"It's one of my biggest successes no doubt," said Ganguly, who became India's most successful Test captain ever after his team won the decisive third Test in Rawalpindi by an innings and 131 runs to clinch the series 2-1.
"This is indeed a very special moment for the team," he said.
"Beating Pakistan is always very satisfying and to win our first ever series on Pakistani soil has to be something big.
"The enormity of it all has not sunk in yet, but I am sure it will over the next three or four days, especially after we return home.
"We have played well over the last few years and it showed in our performance during the tour. First the One-day series came to us 3-2 and now this. It's a dream come true.
"It has taken us a few years to become a good side. We have played well both at home and abroad. All this is a result of the hard work we have put in over a considerable period of time," Ganguly said.
India's first overseas series victory since Sri Lanka in 1993 helped Ganguly surpass predecessor Mohammad Azharuddin's record 14 wins as captain.
"It's an honour to have the record in my name, but that is entirely due to what the whole team has achieved," Ganguly said.
"I will be happier if we can continue in the same vein in future."
Of India's 21 away wins since it started playing Test cricket in 1932, eight have come in the last four years under the team management of Ganguly and his deputy Rahul Dravid.
Dravid was named the Man of the Match for his monumental 270 in India's total of 600, while Virender Sehwag was nominated the Man of the Series after his Indian record of 309 in the first Test at Multan.
India had won the first Test at Multan by an innings and 52 runs before Pakistan drew level with a nine-wicket triumph at Lahore last week.
Ganguly praised his team's all-round effort in which the young seam bowlers, Irfan Pathan and Laxmipathy Balaji, complimented the star-studded batting line-up.
"We have solid batting in our ranks with Sehwag, Sachin Tendulkar, Dravid, Venkatsai Laxman, Yuvraj Singh and myself," he said.
"I have always believed it is important to put up big runs on the board to win a Test match and this we have been able to do consistently.
"But I admired the way Pathan and Balaji performed. It was very hot on the tour, yet both kept their fitness levels high and bowled good, long spells."
Balaji and Pathan finished with 12 wickets each, while leg-spinner Anil Kumble was the most successful bowler in the series with a haul of 15 wickets to take his career tally to 397 from 84 Tests.
India's next Test engagement is a four-Test series against world champions Australia at home in October, followed soon after by another home series against South Africa.