The city has been combined with its neighboring township of Dombivli to form the City Corporation of Kalyan-Dombivli.It is considered a part of the Greater Mumbai metropolitan agglomeration, along with Navi Mumbai and the cities of Bhiwandi, Thane.
As a major entrepot, Kalyan soon became, by 530-535 A.D. the seat of a Nestorian bishop (). The Churches of South Asia which were ecclesiastically dependent on the Church of Assyria and Chaldea in Mesopotamia or modern Iraq, lands then subject to the Persian Empire (Sassanians), early fell with it into the Nestorian Schism and used Pahlavi as the liturgical language. The Konkan, Tulunad and Malabar Coasts of South Asia are marked by stone crosses with Pahlavi inscriptions.
During the Middle Ages, Pope John XX, headquartered at Avignon, sent a group of five missionaries to the Mongol Emperor at Khanbalik, modern Beijing in China, under the Dominican Fray Giordano or Jordanus. On their way, they picked up a novice, Demetrius, from West Asia and then travelled through South Asia, succoring the Nestorian Christians there, who were hard pressed by the Muslims. Giordano left his colleagues at Kalyan and travelled back north to Gujarat. During his absence, the Muslim governor and Qazi of Thane summoned the missionaries and demanded submission to Islam; when they refused, they were murdered (1321). The local Nestorians collected their remains and buried them; Giordano, on his return, took them to Sopara and buried them there. The Muslim Arab sultan of Gujarat, when informed of this development, summoned his governor of Thane and the Qazi; the Qazi fled but the governor was executed for his actions that militated against international commerce. When a later missionary, Oderic of Pordenone (), visited Thane in 1324-1325, he collected their remains and moved on to China.
In the later Middle Ages, Kalyan was occupied by the Ahmednagar Sultanate, an indigenous dynasty founded by a man forcibly converted from a Hindu Brahmin family as a child, and then by the Bijapur Sultanate, an Indo-Turkish state in the Deccan in the 1500s, and later by the Mughals under the Emperor Shah Jahan, who fortified the city in the mid-1600s. It came under Portuguese sway for a brief time before being re-conquered by the Muslim allies of the Mughals, and was later conquered by the Marathas, who made it one of their strategic centers because it guarded the entrance to Mumbai and the western coast of India. Kashibai, wife of the Peshwa Bajirao was born in Kalyan. About eighty years after the Maratha conquest, the Maratha Empire was forced to cede it to the British and Kalyan became part of the Bombay Presidency, a British India province that became Bombay state after India's independence in 1947. In the Middle Ages, when Kalyan was occupied by the Ahmednagar Sultanate, they gave name as Gulshanabad and in the time of Maratha it was changed to Kalyan.
Durgadi Fort (किल्ले दुर्गाडी): It is not known when the Durgadi fort was constructed. The wall of the fort along the top of the inner bank of the ditch, and, near the north end, had a gateway known as the Delhi or Killyacha Darwaja, which was entered by a path along the top of the north side of the town wall. Inside the fort there was a low belt of ground, about the same level, as the top of the ditch, with a shallow pond not far from the Delhi gate. The remains of the pond are still visible, in the north-west corner the fort rose in a small flat-topped mound about thirty feet high. On the top of the mound, on the west crest which overhangs and is about above the river, is the prayer wall or idgah, sixty-four feet long, thirteen high and seven thick, which is now in a dilapidated condition. This doubtful wall is said to be of the old Durga temple wall and is thickly plastered. It is said that near the east crest of the mound there was a mosque, but no remains of it can be traced. About thirty to forty yards of the idgah was a round cut stone wall of great depth, eleven feet in diameter with a wall two feet eleven inches thick at the top, which has now completely, collapsed except the basement of the wall. Under the Marathas (1760-72), a new gate about to the south of the Ganesh gate was opened near the mansion of Ramji Mahadeo Biwalkar, the Peshwa s Governor. In the citadel of the fort Marathas built a small wooden temple of Durgadevi behind the mosque, and called the fort Durgadi Killa in honour of the goddess, a name which it still bears. They also converted the mosque into Ramji's temple. The fort measures in length and somewhat less in breadth. Under the English the fort wall was dismantled and stones carried to build the Kalyan and Thane piers and a dwelling for the customs inspector in the west of the Kalyan fort. The gate to the north-west is almost the only trace of the fort wall, which is of rough stone masonry. During 1876 the original idol of the goddess Durga was stolen. The other idol was placed during the last decade of the 19th century. The present fort as well as the present Durga temple was renovated (jitnoddhar), by the Kalyan municipality on 15 December 1974. A new idol of goddess Durga made if Panchadhatu (five sacred metals) was installed by Shri Gajanan Maharaj and Shri Annasaheb Pattekar of Thane on the same date. The idol is four-armed, three and half feet in height, with a lion resting at its back. To the right of idol is the old idol. The municipality has constructed a new gate high and with four towers. There has also been laid a beautiful garden which surrounds the fort.
The fort, which has now more or less become a picnic spot, gives an excellent view of Retibunder, the creek, the Bhiwandi bridge, the groves near and afar and the hills to the north of the fort.
In and before July 1946 there was a large military transit camp near Kalyan.
Kalyan is also a major Central Railway junction
Kalyan East comprises Lok Vasahat (Lok Gram, Lok Dhara and Lok Vatika), Patripul Slum Area, Chakki Naka, Sastri Nagar, Chetna, Sunrise Valley, Nandivili, Netivali Area , Chinchpada, Hanuman Nagar, Katemanivali, Kolsewadi, Vijaynagar, Tisgaon, Siddhartha Nagar, Karpewadi ,new jimmy baug and Patripool area (Ramabai Ambedkar Nagar Area), and the Metro Junction Mall
Kalyan West comprises Station Area (Nehru Chowk), Laxmi Vegetable Market, Rambaug, Shivaji Chowk, Bail Bazar, Shankar Rao Chowk, Ahilyabai Chowk, Tilak Chowk, Gandhi Chowk, Sathe wada, Sahajanand Chowk, Agra Road, Parnaka, Dudhnaka, Lal Chowki, Bazar Peth, Adharwadi, Durgadi Area, Murbad Road,syndhicate, Chikkanghar, Karnik Raod,kala talav, Rambaug Lane [0,1,2,3,4,5,6], Joshibaug, Yogidham, Khadak Pada, Birla College Road,Beturker Pada,Thangewadi,Ramdaswadi,Gandhari,Purnima Naka,Vayale Nagar,Mhasoba Maidan,Sahyadri Nagar,Godrej Hills Area, some part of Shahad.