Before you start

An unlocked handset
Passport, for registration
A Czech address and bank account, for a postpaid contract

Step-by-step

1
Use EU roaming as a bridge
Arriving from another EU country, your existing SIM works here at domestic rates under roam-like-at-home. There is no day-one pressure, so compare properly rather than buying at the airport.
In personWho: You
2
Buy a prepaid SIM when you are ready
Available from operator shops, supermarkets and kiosks across Brno. Registration requirements are lighter than in most of the region but you should carry your passport.
In personWho: YouCommonly CZK 200–500 including starting credit
3
Look hard at the resellers
Kaktus and Mobil.cz run on the major networks at noticeably lower prices, generally without contracts. Czech headline network prices are above regional norms, so the saving is larger here than the equivalent choice would be in Poland or Germany.
OnlineWho: You
4
Move to postpaid only once you have an address and bank account
Contracts require a Czech address and bank account for direct debit, and sometimes a residence permit. There is no reason to rush into one, and 24-month terms are the norm.
In personWho: You
5
Order home internet early, and check the building first
Brno's newer buildings and the panel estates are generally well served by fibre or cable. Older centre-city buildings vary, and in a shared building the connection may depend on what the owners' association has already allowed. Ask the landlord what is installed before you sign, rather than what is theoretically available at the address.
OnlineWho: You
6
Check coverage where you will actually go
Urban coverage across Brno is strong on all three networks. The Moravian Karst valleys north of the city, where you will spend weekends, are patchier and the operators differ. If that matters to you, compare the coverage maps for those specific valleys rather than for the city.
OnlineWho: You

Documents you’ll need

Passport
Czech address and bank account, for postpaid
Residence permit, sometimes requested for a contract

Things most newcomers don’t know

Czech mobile is pricier than neighbouring Poland, so the resellers matter more here.

The three main networks price above regional norms. Kaktus and Mobil.cz run on the same infrastructure for substantially less, with no contract. This is not a marginal saving — over a year it is meaningful, and the coverage is identical because it is the same masts.

Source: community-reported, corroborated by EU price comparisons

EU roaming removes any day-one pressure.

Your existing EU SIM works in Czechia at domestic rates under roam-like-at-home rules. That means you can compare plans after you have an address and a sense of what you actually use, rather than buying whatever the airport kiosk has. People overpay for months because they bought in the first hour.

Source: EU roam-like-at-home rules

In an older Brno building, ask what is installed rather than what is available.

Coverage checkers report what an operator can theoretically serve at an address. In a shared older building in the centre, whether fibre actually reaches your flat depends on what the owners' association has permitted and what was physically run. Ask the landlord to name the provider and the connection type in the listing conversation, not after you have signed.

Source: community-reported

Coverage is strong across the city and thinner in the Karst.

All three networks handle Brno itself well, so choose on price. The limestone valleys of the Moravian Karst thirty minutes north — where a great many Brno residents spend their weekends — are patchier and the networks differ. If you walk or climb there regularly, that is the map to compare rather than the city one.

Source: community-reported

Common mistakes to avoid

Paying airport prices when EU roaming already covers you at domestic rates.
Signing a 24-month contract before you have an address and bank account.
Paying premium-network prices for coverage a reseller provides identically.
Assuming an address checker's answer means the connection actually reaches your flat.
Choosing a network on city coverage when you will spend weekends in the Karst.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.