The Dutch-owned group, brainchild of Mexx fashion tycoon Rattan Chadha, pioneered an "affordable boutique" model in the UK based on low construction costs and highly styled rooms and public areas. Its 198-room hotel in Cowcaddens, which opened in 2010, was its first foray into the UK.
The upgrade to the Glasgow hotel, which also includes equipping each room with Samsung tablet computers, is part of a worldwide investment programme which will see the group open London properties near the Tower of London and St Paul's Cathedral, in addition to new hotels in New York and Paris.
Robin Chadha, Citizen M's chief marketing officer, said the group remained committed to strong partnership with "Team Glasgow", including strategic partnership such as that with the Glasgow School of Art, whose recent degree show it supported.
The hotel brand is pitched at design-conscious travellers and includes enhanced status for frequent users, allowing use of business-friendly members' meeting and working areas.
Chadha was careful to praise Glasgow's dynamism and sophistication, as well as Citizen M's record of collaboration with the civic marketing and tourism authorities. The emphasis was in part a response to recent media reports of negative remarks by the owner about the drinking habits of Glasgow clientele sitting awkwardly with Citizen M's target demographic of globe-trotting urban sophisticates.
The remarks referred to the need to employ extra door staff to counter the tendency for late-night patrons regularly to fall down Citizen M's soon-to-be-replaced spiral staircase.