Alex McDougall, 77, originally from Scotland, died earlier this month at a care home in Nottinghamshire.
Carers invited anyone with connections to the Army or Mr McDougall's football team Glasgow Rangers to attend.
Broxtowe Borough Council said it had been "overwhelmed" by the public support but warned space was limited.
Staff from the Beeston Fields Care Home appealed for mourners on social media over fears the funeral, which took place at Bramcote Crematorium, would only be attended by a limited number of staff.
Deborah King, from the home, said: "It's so nice that people that have been in the military, veterans and those serving, are taking an interest and showing there are kind people out there.
"He would probably be quite overwhelmed by it all."
Andy Harrison, who is with the Royal Engineers, said it was important to honour a former soldier.
He said: "There's countless others from the station [Chetwynd Barracks} who will be going down... we can't allow his passing to go unmarked."
Sarah Teale, reporter, BBC East Midlands Today
It was quite a moving sight.
There was standard bearers from the Royal British Legion, many people in uniform and the Royal Artillery Corps, some from the Chetwynd Barracks and just members of the public.
They didn't want a funeral where he would be all alone.
They brought flowers, they brought wreaths and more importantly brought the numbers.
The borough council said it was "overwhelmed by the public show of respect" but warned that parking space was limited and the small chapel could accommodate just 46 people.
Mr McDougall moved to the county's Chetwynd Barracks, in Nottinghamshire, from Scotland when he joined the Army at the age of 21.
He spent 18 years at the home and died from cancer.
Hundreds of people have attended the funeral of a former soldier who had no known family or friends after a social media appeal.