Restrictions on indoor household gatherings have been extended to two other local authority areas: Renfrewshire and East Dunbartonshire.
The two council areas join Glasgow City, East Renfrewshire and West Dunbartonshire, where the ban on hosting or visiting other households will be continued for another week.
The restrictions come into force in Renfrewshire and East Dunbartonshire from midnight.
It comes amid a surge of coronavirus cases in the west of Scotland in recent weeks, primarily driven by private household gatherings.
Such gatherings were banned other than for emergencies, extended households or care for vulnerable people on September 1 in Glasgow, East Renfrewshire and West Dunbartonshire.
Now, with the addition of Renfrewshire and East Dunbartonshire, the restrictions are affecting more than a million people.
Indoor visits to hospitals and care homes in these five local authority areas are also limited to essential visits only.
Outdoor visits to care homes are permitted by three people from a maximum of two households, in line with current guidance.
And in a further measure, if anyone living in these five areas is identified as a close contact of someone who has tested positive for Covid-19, they and everyone in their household should self-isolate for 14 days.
There have been more than 700 new coronavirus infections in the NHS Greater Glasgow and Clyde region over the last 14 days, and nearly 250 in Lanarkshire.
Prevalence rates had been especially high in the city of Glasgow, East Renfrewshire and West Dunbartonshire council areas.
Announcing the extension of measures, First Minister Nicola Sturgeon said: “A week on, we continue to see cases in these council areas increase and it’s too early to say whether these restrictions have yet had the effect.
“So the Scottish Government resilience committee has just met and decided to continue these restrictions in these three council areas for a further week.
“However, in addition to that, in light of rising incidence of the virus in Renfrewshire and East Dunbartonshire, we have taken the decision to extend those restrictions to those two council areas as well.
“So if you live in East Dunbartonshire or Renfrewshire council area, then these restrictions from midnight tonight apply to you as well.
“In summary, that means you should not have people from other households in your home and you should not visit other people’s houses.”
She added: “It’s regrettable that we are in this position but we do see rising transmission, and if we act quickly and preventatively now then the hope is we will stem the tide of transmission and avoid the need to have any further restrictions being put in place.”