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40 Sweet Words to Wish “Happy Birthday” to Your Sister-In-Law

40 Sweet Words to Wish “Happy Birthday” to Your Sister-In-Law

Your sister-in-law deserves to feel loved by her newly-adopted brother or sister on her birthday. Dropping a quick ‘happy birthday’ to your sister-in-law will show her that she’s in your thoughts and wish her nothing but the best.

There are many ways to say ‘happy birthday, my sister-in-law.’ Here are 40 of them.


Wishes for your sister-in-law who is your husband’s younger sister

If you want to say ‘happy birthday, my sister in law’ to the younger sister of your husband, take a look at these 15 birthday wishes:


01As you know, I have all brothers so, finally having a sister feels like a breath of fresh air! Happy birthday, my sister-in-law, who I already consider a baby sister.


children brothers and sisters
Photo by Alexas_Fotos under pixabay license


02Happy birthday, my sister-in-law. You always give me a reason to smile with all your crazy antics and silly jokes. I just love having you around!


03To my cute little sister-in-law: have a happy birthday, you beautiful, intelligent young lady. I hope that your next year brings you only happiness.


04I am so glad my husband’s little-sister didn’t turn out to be a little demon! You are the most adorable little girl, and I know you will grow into an amazing woman. Happy birthday, princess!


young woman girls selfie selfie funny makeup crazy sisters happy selfie

Photo by Victoria Dupont on reshot


05On this special day, I want to send you best wishes and good fortune. I hope you get all that you wanted for your birthday!


06Since I married your brother, I learned so much about you. I learned that you are caring and smart and also funny and talented. I am proud to call you my sister-in-law. Happy birthday!


sisterhood sisters kiss

Photo by Sasha Ivanova on reshot


07One of the best parts of this marriage was getting a younger sister! Happy birthday, my sister-in-law!


08Of all my new in-laws, you are, without a doubt, my favorite! Thank you for being so kind and receptive to my joining the family, and I wish you a very happy birthday.



09Today is a day to celebrate the day you came into this world. You are truly a blessing, Moya! I hope you have an awesome birthday.


sisters sister baby toddler child
Photo by timkraaijvanger under pixabay license


10The day I said ‘I do’ to your brother is the day I formally gained a new sister. And I am so thankful. Have a wonderful, joy-filled birthday, my sweet sister-in-law!


11When your brother introduced me to his family, you were, by far, the most welcoming and inviting member of the group.
You made sure I was comfortable, and you always went the extra mile to include me in whatever you guys had going on. You are indeed a brilliant young lady, and you are more than deserving of a happy birthday!


children garden autumn play fun

Photo by 1494202 under pixabay license


12Happy birthday, my sister-in-law! Today we celebrate you and your life, and how grateful we all are that you are a part of our own lives.


13I hope you are ready for the fun-filled day I have in store for you, my sweet sister-in-law! It’s going to be a blast! Happy birthday!


14Even though we just met, I can already tell that we will get along famously. Happy birthday, my sister-in-law.


15Without you, I don’t think my husband would have learned to be so patient, understanding, and kind.
His best features grew from how he took care of his baby sister. Thank you for helping to make him into the man I love today. Have a tremendously happy birthday!


brothers and sisters brother sister

Photo by RondellMelling under pixabay license


Birthday-wishes for your sister-in-law who is your husband’s older sister

To say ‘happy birthday, my sister-in-law’ to your husband’s older sister, use one of these birthday messages.


16Happy birthday, my sister-in-law, who is always there to guide me. I’m so glad you came into my life.


sisters hug happy photo

Photo by Lucas Lenzi on reshot


17Whenever I am down, I know I can always come to you for advice. You are wise and kind, and I couldn’t have asked for a better addition to my family. Happy birthday, my sister-in-law!


18I’ve always admired how well put together you are, and how you are always up to something new! You are a true inspiration to me, my dear sister-in-law. Happy birthday.


19I am so happy I get the be the sister-in-law of a strong, independent woman like yourself. You are worth all the love and happiness that I know your birthday will bring. Best wishes!



20To my dear sister-in-law: I hope today will be an amazing day for you. Happy birthday!


celebrate wine glass raise happy people
Photo by Kelsey Chance on unplash


21Best wishes to my fabulous sister-in-law on her 50th birthday! I know that your ‘golden years’ will be as shimmering and beautiful as all your others. Happy birthday!


22A birthday is the beginning of a new chapter in one’s life, and I am so happy that I get to be a part of yours. Happy birthday to my new big-sister and friend.


23To me, you are not just my brother’s older sister. You’re an amazing advisor and a cherished friend. Happy birthday, my sister-in-law.


two white americans one black american friends

Photo by Omar Lopez on unsplash


24I wish you endless happiness and joy on this, your 30th birthday. You are a wonderful woman who deserves an abundance of blessings and good fortune.


25My husband is so lucky to have such an incredible sister backing him, and I feel honored to be a part of your life. I look forward to seeing you at your birthday get-together later. I know it will be a lot of fun.


26I know we have had our run-ins in the past over differences of opinion, but I have never held that against you. In fact, I quite admire you and look forward to becoming great friends in the future. Happy birthday!


27I hope your birthday is as special as you are. I am always so proud to introduce you to others as my sister-in-law. You are the epitome of kindness and bring light to this dark world.


photos polaroid shots

Photo by Hannah Gentry on reshot


28You have always been someone I can lean on, even when I am at odds with your brother. I appreciate everything you have done for me and wish you a peaceful and pleasant birthday.


29You are someone who understands me and someone who I can always lean on. You’ve become the big sister I never had. You’re a gift from God. Happy birthday.



30When I reflect on my marriage with my husband, I can’t help but remember all the times you were there for us, even through the most difficult moments.
You have earned all the good things in your life, and I wish that you continue to be blessed on this, your birthday, and each day that follows.


Birthday wishes for your sister-in-law who is your wife’s younger sister

If you are a husband looking to say ‘happy birthday’ to your wife’s younger sister, here are 5 birthday wishes you can use.


31They say younger sisters can be extremely territorial of their older sister, and they were right!
I love that you gave me a tough time in the past because of how much you love your sister. I am so glad that you can finally see that I love her as much as you do. Happy Birthday, Lilly.


children sisters cute fun girls
Image from Pexels under pexels license


32Happy birthday to my little sister-in-law. I think of you as my own baby-sister.


33To my sweet and loving sister-in-law: happy birthday!


Birthday confetti 25 balloon

Photo by Kawamura Mot on reshot


34Congratulations to my sister-in-law on finally crossing the 18-year mark! You have lots of great years ahead of you, kiddo! I know you will blossom into a smart and beautiful young lady, just like your sister.


sparkling cherry pie

Photo by Lucy Heath on unsplash


35I am so happy to be able to celebrate your birthday with you, sister-in-law. You have really grown on me in these few short months.


Birthday wishes for your sister-in-law who is your wife’s older sister

For your wife’s older sister, you can send her birthday wishes like:


36When I met your sister, I thought she was the most wonderful person in the world, but now I know the trait runs in the family. Happy birthday, my sister-in-law.


Birthday girl cake happy woman

Photo by Chloé Boulos on reshot


37I have always wished for a big sister, and when I married your sister, God granted me that wish. You could not be more perfect! Happy birthday.


38Dear sister-in-law, I wish you a fantastic birthday and a fabulous year.


39I am truly blessed to have a supportive, caring, and loving sister-in-law who I know I can always count on. May your birthday be full of love and happiness, and I hope all your wishes come true.


strawberry roll strawberry cake slice

Photo by RitaE under pixabay license


40Happy birthday to my favorite sister-in-law! Although I won’t get to spend your birthday with you, I wish you nothing but the best and a day of enjoyment.



Now that you have your ‘happy birthday, my sister-in-law’ wishes on lock, you can put your thoughts and energy into getting her a wonderful present.

But, if you chose well and sent a message filled with heart, perhaps these sweet words will be more than enough!