It is linked to Deansgate-Castlefield tram stop and the Manchester Central Complex by a footbridge built in 1985; Deansgate Locks, The Great Northern Warehouse and the Museum of Science and Industry are also nearby.
The platforms are elevated, reached by lift or stairs, or by the walkway from the Manchester Central Complex. The ticket office, staffed full-time, is between street and platform levels. There are no ticket barriers, although manual ticket checks take place on a daily basis.
It is on the Manchester to Preston and the Liverpool to Manchester lines, both heavily used by commuters. Most tickets purchased by passengers to Deansgate are issued to Manchester Stations or Manchester Central Zone, therefore actual usage is not reflected in these statistics, due to the difficulty in splitting the ticket sales correctly between the four grouped stations (Piccadilly, Victoria, Oxford Road and Deansgate).
The original station buildings were situated on Hewitt Street. The station was opened as Knot Mill and Deansgate on 20 July 1849 by the Manchester, South Junction and Altrincham Railway (MSJAR) near the Manchester terminus ('the Knot Mill station') of the Bridgewater Canal from which in 1849 travellers could catch a fast packet which could get them to Liverpool in four and a half hours for as little as sixpence. (The fare was anomalously low because of a temporary outbreak of competition between the canal and the London and North Western Railway (L&NWR); it was back up to sixteen pence by 1853).
When a celebratory train ran over the line at the start of July 1849, a reporter for the Manchester Courier noted that most stations had permanent buildings and "at Knott Mill and Oxford-street temporary stations will in the meantime be erected". When the line opened for passenger traffic a fortnight later, the Courier duly noted that the station at Knott Mill had opened with temporary wooden buildings.  The booking office was at street level; from it "narrow, steep, troublesome steps, enough to tire anyone but athletes" led to the platforms. The station proved - according to its critics -to be "inconvenient of approach, ugly in appearance, and with platform, booking office, and waiting-room accommodation much cramped" but accessibility was the biggest issue: for the aged, the invalid or children it was "a most difficult not to say dangerous task to climb the steep flights of steps to the platforms."
(The area was also the site of the annual Easter-tide Knott Mill Fair, a decades-old event, which (until its abolition in 1876) hosted acts such as Pablo Fanque's Circus Royal and George Wombwell's Menagerie. In 1860, special trains laid on in connection with the fair by both the L&NWR and the Manchester, Sheffield and Lincolnshire Railway (MS&LR), the joint owners of the MSJAR were not advertised as running to Knott Mill station; the LNWR excursion ran to Ordsall Lane, the MS&L excursion to London Road.)
If the station was originally named "Knot Mill and Deansgate" by the MSJAR, from its opening onwards it was simply 'Knott Mill' (or 'Knot Mill') to the Manchester papers and by 1860 the railway was following suit in its advertisements. In 1864, the MS&LR gave the required notice of a bill to be brought forward in the next session of Parliament for widening part of the MSJAR "from or near Knott Mill Station to Old Trafford Station"; however in the same year the accident return for an accident at Old Trafford noted that the train involved had stopped at "Knot Mill, and left that station..."