Scottish artist Stephen Shankland has won the BP Portrait Award 2004 for a portrait of his wife and child.
He was awarded £25,000 in prize money and a £4,000 commission at London's National Portrait Gallery on Monday.
His portrait was entitled The Miracle in honour of 17-month-old son Connor, who was born so prematurely in January 2003 that doctors feared he would die.
The works of all four shortlisted artists will be on display at the gallery until 19 September.
"The Miracle is a painted tribute to the strength and courage of my wife and the strong will to survive of my son," Mr Shankland said.
"After spending a month at our son's bedside following his birth with a diaphragmatic hernia, doctors nicknamed him 'the little miracle'."
The director of the National Portrait Gallery, Sandy Nairne, described the portrait as "exquisitely painted".
"It is an emotional painting and a worthy winner in a year in which there was very tough competition."
In second place, winning £8,000, was Herefordshire-based artist and stonemason Paul Harris, for his portrait of his business partner Louise Tiplady.
Fergus Mayhew won third prize for Head Full of Smiles, a portrait of his mother, Bunty, marking the first time the Devon-based father has been recognised at an awards ceremony.
Syrian artist Sara Shamma won fourth prize for Self-portrait, part of an ongoing series.
The portrait competition is in its 24th year, and this year received a record 955 entries.
"The superb quality of these winning paintings, together with the record number of entries for this year's prize, demonstrates again the vitality and health of portraiture today," said Des Violaris, director of UK Arts and Culture at BP.
The BP Travel Award, an annual award of £4,000 for young artists, was won by Darvish Fakhr who proposes to travel to Iran and paint portraits of local people in the old Persian bazaar.
An exhibition featuring the winning works will travel to the Royal Albert Memorial Museum in Exeter in October, and then to Aberdeen Art Gallery in December.
The 2003 Travel Award winner, Ulyana Gumeniuk, who used her prize money to paint portraits of fellow Ukrainians, will also exhibit alongside this year's winners.