The price of a single ticket on the system will increase from £1.20 to £1.40, as tariffs across the board face a hike for the first time since 2009.
Fares across the six Subway ticket types will go up by 9%, almost three times the rate of inflation, while the cost of a single, which accounts for almost half of all tickets sold, is nearly five times the figure.
A return will rise from £2.40 to £2.60, while a 20-journey ticket will be £22, up from £20.
The Subway's operator, Strathclyde Partnership for Transport (SPT), is expected on Friday to approve the rise, which it said was in large part due to a drop in user numbers. It attributed this to the slowdown in the wider economy.
The system lost around 120,000 passenger journeys in the past year, with the biggest monthly drops recorded over the busy shopping period of November and December.
SPT said it expected further economic difficulties to hit Subway numbers, meaning prices needed to rise for those who still choose to use the service, to maintain income levels.
The transport body defended the rise by claiming that fares on the network have remained unchanged for the past three years, during which time rail and bus fares have increased in price by 12%.
Meanwhile, fares on bus routes subsidised by SPT will also go up, by 5%, and MyBus or Dial a Bus fares will increase from £2.00 to £2.50.
Malcolm Balfour, Glasgow SNP councillor and SPT partnership member, said the hike could be self-defeating, driving people away from the Subway.
He said: "The proposed increase in Subway fares has the potential to put passengers off using the service. Although perceived as only a 9% increase across the board, it is in real terms a 17% rise on the single adult fare at a time when the public are already finding it hard to make ends meet. In comparison, rail fares are only going up by 1% above inflation. I am concerned that this will have an adverse effect not only on the people who use the Subway on a regular basis but also on visitors to this city in the run up to the Games in 2014, and I will call on SPT to review this increase or at least consider phasing it over time."
In his report to SPT partnership members asking approval for the rise, Eric Stewart, SPT's assistant chief executive, said: "It is also recognised that Subway patronage and revenues may be impacted upon by the current economic climate, and whilst the impact of these factors is difficult to predict, it is vital that the Subway ticketing and fares offering has the flexibility to stimulate the required growth.
"With Subway fares having remained unchanged since 2009, members are recommended to approve a general increase of around 9%. This maintains Subway fares at a level still well below equivalent bus and rail fares. One of the key fundamental aims of Subway modernisation is to reduce subsidy. The review is part of an ongoing process to ensure SPT's Subway ticketing and fares policy provides good value for the travelling public and to the public purse."