In a statement, the World Trade Organization said Norway and Canada had both filed appeals on Friday. In general, WTO appeal rulings are issued within three months.
In November, the WTO disputes settlement body ruled that while there was merit in Norway and Canada's complaints over the 2010 EU ban, that was outweighed by the goal of addressing moral concerns about seal welfare.
Brussels argues that the EU public overwhelmingly favours the ban, and that scientific evidence back claims that slaughter methods, such as using a club with a metal spike on it to stun seals before killing them, are cruel.
Norway and Canada have deployed counter-arguments from scientists, insisting that their seal-hunting methods are humane and no worse than those used in commercial deer-hunting, widespread in the EU.
They both kill tens of thousands of seals per year, and say hunting is an age-old method allowing Atlantic fishing communities to earn an income, as well as to manage fish stocks and thereby the environment.
They also say the ban is trade discrimination because seal products from EU members Sweden and Finland enjoy unimpeded market access within the 28-nation bloc. The EU rejects that argument.
Canada's indigenous Inuits, who have traditionally hunted seal for centuries, are exempt from the ban but say it has ruined the market for their seal products too.
In addition, the ban's adversaries warn that the moral grounds defence justifying it could be applied to a host of other products, thus upsetting trade flows.
The WTO polices global trade accords in an effort to offer its 159 member economies a level playing field.
Disputes at the WTO are often extremely technical and can last for several years amid appeals and assessments of compliance with its rulings.
The WTO's disputes settlement body, made up of independent trade and legal experts, has the power to authorise retaliatory trade measures against a country found at fault and which fails to fall into line.