England and Scotland players wore armbands featuring the symbol when they met at Wembley on 11 November.
Wales and Northern Ireland's respective games featured displays on the pitch or in the stands to mark the event.
England's Football Association will appeal against the fine of 45,000 Swiss francs (£35,311), with Scotland, Wales and Northern Ireland yet to decide.
Scotland and Wales were both fined 20,000 Sfr (£15,694), and Northern Ireland 15,000 Sfr (£11,770).
A Scottish FA (SFA) spokesman confirmed discussions between the home nations have already taken place and an official appeal is likely to be lodged early in the New Year.
Fifa disciplinary committee chairman Claudio Sulser said he "fully respected" the commemorations but stressed the rules "need to be applied to all member associations".
"The display, among others, of any political or religious symbol is strictly prohibited," he added.
"In the stadium and on the pitch, there is only room for sport, nothing else."
Sports Minister Tracey Crouch described Fifa's decision as "disappointing".
Why have the countries been punished?
According to the rule-making International Football Association Board (IFAB), players cannot wear "political, religious or personal slogans, statements or images".
But both England and Scotland players wore armbands featuring the poppy symbol during England's 3-0 win.
There was also a display of poppies on big screens, a minute's silence, playing of the Last Post and poppy T-shirts handed to the crowd.
Following Wales' 1-1 draw at home to Serbia the next day, Fifa opened disciplinary proceedings looking at "fans in the stands wearing the poppy" and the presence of "a member of the armed forces holding a bunch of poppies at the exit of the tunnel", according to the Football Association of Wales (FAW).
The holding of a minute's silence, the laying of a wreath and a poppy display by fans before Northern Ireland's 4-0 win over Azerbaijan on 11 November have led to the punishment of the Irish FA.
Fifa has also punished the Republic of Ireland (FAI) with a 5,000 Sfr fine (£3,930) after its players wore shirts commemorating the centenary of the Easter Rising earlier this year.
How have the home nations responded?
An FA spokesperson said: "We note the decision by the Fifa disciplinary committee, which we intend to appeal. As a first step, we have written today to Fifa requesting the grounds for the decision."
SFA chief executive Stewart Regan says it is "clearly disappointing" that Fifa has ruled the poppy is a political symbol.
The SFA board will discuss the issue on Tuesday to decide on any appeal and will request the full reasons from the governing body.
The Irish FA (IFA) said it was "disappointed", although they cannot appeal as their fine is under the Fifa disciplinary code limit.
The FAW has yet to respond.
Sports Minister Crouch said: "It is disappointing that Fifa has not recognised the sentiment of the poppy, which is not a political symbol.
"Poppies are a poignant tribute to the bravery and sacrifice of our servicemen and women, and footballers and fans alike should be able to wear them with pride."
Shadow sports minister Dr Rosena Allin-Khan MP described Fifa's decision as "utterly disrespectful".
How did we get here?
In 2011, Fifa agreed that the England, Scotland and Wales teams could wear poppies on black armbands during November internationals.
England wore them during their 1-0 friendly win over Spain at Wembley, Scotland did so in a match against Cyprus and Wales wore them against Norway.
However, this year, under new president Gianni Infantino, Fifa indicated they could punish teams for breaking the rule before the November matches.
That led to UK Prime Minister Theresa May calling Fifa's stance "outrageous"," adding that it would be "absolutely right" for players to wear poppies.
A points deduction was also a possible punishment open to Fifa.