It's their den, their base camp and the room they spend the greatest chunk of their time in (even if much of it is when they're asleep), so you and they will want it to be as fabulous as possible. Many children's rooms are also on the small side, yet need to be a place to store not just clothes but toys and to hang out and play in.
So how can you create a space that works and looks great, without it costing so much that it makes you want to retreat into your own room to weep into your pillow?
Whether you're decorating a baby's room for the first time, or revamping an older child's, here's our guide...
1. Think long term.
Avoid spending too much on anything that will be outgrown within a few years. Culprit number one here is scaled down nursery furniture. Yes it looks sweet and it might have shelves that are slightly more accessible for a preschooler but in a few short years, you'll wish you'd bought something full-sized with more longevity.
The stage when a child is able to get their own clothing out of drawers or wardrobes but can't reach into a proper wardrobe or drawer chest with a step stool is really very short.
Stick with full-sized grown-up furniture that wouldn't be out of place in a teenager or adult's room and you'll thank yourself in eight or 10 years' time.
2. If you're buying for a baby and their room is pretty cramped, consider a cot-bed.
These are slightly larger than cots at 140x70cm versus 120x60cm so take up more floorspace in the short term but are worthwhile if fitting a single bed in will be a squeeze later on. They convert to a junior bed suitable up to around age five and at this stage will take up less space than a proper single.
Note though that they won't save you cash overall as you'll still need to buy a single anyway, it'll just delay the purchase. If your child had a cot not a cot bed, avoid buying a junior bed as it's an unnecessary extra expense - go straight to a grown-up single.
As children get older, the amount of stuff they accumulate tends to increase and more of it is likely to be kept up there in their own bedroom (hurray, no more tripping over discarded toys in the living room!)
The space under the bed isn't just for hiding – get wooden under-bed storage drawers or cheap plastic versions from DIY shops or large supermarket home sections (ideally with lids to make dealing with dustiness easier!).
Use wall space for storage as well as decorations - Tidy Books has some clever wall-hung book shelves from £44.95. It also specialises in bookcases and storage for children's rooms.4. Don't go overboard with expensive themed products that might not work for an older child.
Winnie the Pooh wallpaper and curtains might seem cute for your newborn but when they're a five or six-year-old schoolboy, they'll probably be begging you to redecorate with something less babyish.
Future proof their bedroom by creating a blank canvas with painted walls in a neutral colour and curtains that are plain, striped or checked. Then add interest with cheaper items such as lighting, duvet covers or pictures.
Before making any major purchases, ask yourself 'can I imagine this in a seven-year-old's bedroom'?
5. Wall stickers are our number one tip for making that blank canvas more interesting.
Try Not on the High Street, Bouf and Amazon. Be warned larger ones can be tricky to apply properly so follow instructions carefully.
6. Add a splash of colour with lighting, rugs, bedding and cushions.
There are a plethora of gorgeous home products for kids out there so - we particularly love Ikea for this sort of thing.
7. There isn't a pastel rule.
If you're decorating a nursery for a new addition to the family, baby blue and pink have been traditional choices but brighter, bolder accessories are funkier and more fashionable.
There's no real reason to stick with pastels – your baby won't literally lie awake at night just because their nursery has some vivid hues.
They're super-practical too, packing in desks, storage and even seating all in the 'footprint' of a single bed - check out Room to Grow's selection. Multi-functional marvellousness!
9. Encourage frames, if you can.
Posters bluetacked to the walls, let's face it, don't look great and some adhesives can damage paintwork. Of course older children will want to choose what goes on their walls but compromise by encouraging posters to be displayed in frames. Cheap ones are available at Ikea.
10. If your children share a room, create a little bit of their own territory for each of them.
Interiors stylist and journalist Anna Tobin writes the Don't Cramp Our Style blog about family life in a smaller home and says: "Not long ago, two, three or even more siblings used to have to share a room. Now there is this idea that all children need their own space, but they can still do this even in a small room.
"My daughters play together and alongside each other in their shared bedroom, but their bunk beds are their own individual territories. They don't allow each other on to their particular part of the bunk. They have personalised these areas with their own artwork and stickers and it's where they retreat to when they want to be alone."
Have a look at our gallery below for product ideas for your child's bedroom...