What to Write in a Big Sister Book (60+ Examples)

You made us a family of three — and now you're making us a family of four.

Being your big sister is the best job in the world, and you're going to be amazing at it.

No matter how many little ones join our family, you will always be our first love.

The day you became a big sister, the whole family got a little bigger and a lot luckier.

You will always be our first baby — and now you get to help teach the next one.

You're kind, you're brave, and you're going to be the best big sister ever.

Welcome to the most important, most loving new title of your life: big sister.

Your little sibling is so lucky to be coming home to you.

May you always remember: you were loved first, and you are loved always.

Being a big sister means being a first friend for life.

You've been practicing with dolls — now the real adventure begins.

Our hearts didn't shrink to make room — they grew. And so will yours.

We promise: we will always see you, hear you, and love you. Always.

You're not just getting a sibling — you're getting a lifelong best friend.

We are so proud of the big sister you are becoming.

You'll hold hands, share snacks, and sometimes argue about socks. All of it counts.

There is no one we'd rather trust with our newest little one than you.

Thank you for being patient with us while we figure out the new baby, too.

We love you as much today as we did yesterday. And tomorrow, even more.

Big sister is a forever title — and you wear it beautifully.

Congrats on your promotion — you are now a big sister, effective immediately.

New sibling job description: loud, tiny, adorable. Hours: all of them.

Heads up: your toys are now communal property.

You're going to be the best big sister. Also, you have way more power than you realize.

Welcome to the big-sister club. Motto: 'Don't tell mom.'

You've been upgraded from only child to chief in command.

Warning: side effects of becoming a big sister may include sharing the bathroom forever.

Congratulations — you are now the official sock-finder of the household.

Big sisters: the original babysitters with unpaid overtime.

Remember: you are older, wiser, and allowed to tattle.

New position, same paycheck. Good news: the perks are unlimited baby cuddles.

You've been training for this role with your dolls for years. Congrats, boss.

Fine print of big-sisterhood: one day, you'll have to share the last cookie. Maybe.

Pro tip: the baby cannot yet argue back. Enjoy this era.

Your sibling is about to think you are the coolest person alive. Use your powers for good.

Welcome to a lifetime of being asked, 'why are you the favorite?'

New rule: whoever makes the baby laugh gets the good snack.

You are now officially the oldest. Power move.

You're not losing a lap — you're gaining a lifelong fan club.

You're going to rock at this. Also, your parents may need snacks.

A sister is a gift to the heart, a friend to the spirit. — Isadora James

Sisters by heart, friends by choice.

Being a big sister is the greatest gift, and the greatest title.

There's no better friend than a sister. — Christina Rossetti

Sisters share the same childhood, the same secrets, the same silly jokes.

A sister is the first friend you'll ever have.

A sister is both your mirror — and your opposite. — Elizabeth Fishel

Big sisters teach us that love means sharing and showing up.

Having a sister is like having a best friend you can't get rid of. — Amy Li

A sister is a little piece of childhood that can never be lost.

Today you became something even bigger than yourself.

Having a little sibling makes every story twice as long and twice as beautiful.

Being a sister means being part of every important day of someone's life.

You were somebody's answered prayer.

Your love will be her first language.

Sisters are different flowers from the same garden.

You were the first face of family your little one will know.

The greatest gift our parents ever gave us was each other.

Side by side or miles apart, sisters are always connected by heart.

Where there is great love, there are always miracles. — Willa Cather