Mr Howard described the former cabinet minister as a "great all-rounder" of the coalition who was committed to reform, particularly regarding industrial relations during the waterfront dispute of the late 1990s.
He remembered his former cabinet colleague as a wonderful friend he greatly admired, with a laid-back sense of humour and a special personality.
The father of four and former defence minister died in early November aged 72 after a long battle with Alzheimer's disease.
Hundreds of family, friends, Liberal Party stalwarts, senior figures in the federal government and members of the public attended the memorial service at St Andrew's Church in Brighton on Thursday.
Besides Mr Howard, other senior politicians who paid their respects included former governor-general Sir Peter Cosgrove, Attorney-General Mark Dreyfus, Opposition Leader Peter Dutton and former treasurers Peter Costello and Josh Frydenberg.
Mr Reith joined the Young Liberals at the age of 16 and served as the member for Flinders, on Victoria's Mornington Peninsula, from 1982 to 1983 and again from 1984 to 2001.
He was the Liberal Party's deputy leader from 1990 to 1993 and served as a minister in the Howard government, having the portfolios of industrial relations, small business, employment and workplace relations, and defence.
Former adviser Ian Hanke remembered Mr Reith as a reformer who took on the biggest challenges of the day, fought for the rights of the individual and never got angry or lost his composure.
"He drew the best out in people," Mr Hanke said.
After leaving politics in 2001, Mr Reith was a political commentator and served as a company director.
On Thursday, flags at government buildings in Victoria and the Australian Capital Territory were flown at half-mast in remembrance.
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