Books for 9 yr old dd.. she thinks books her age are babyish !

And, as usual, can recommend the mighty girl website for reading lists.
Use your public library for digital borrowing.

Caroline Laurence Roman Mysteries historical detective fiction with tween protagonists.

I have a nearly-9yo DD who has also enjoyed the Wimpy kid series and HP books. Other titles/series she's recently enjoyed:
Laura Ingalls Wilder (you may need to discuss some of the content with her if she doesn't know the history surrounding the story, but also because a few parts are quite racist)
Varjak Paw
Holes by Louis Sachar (again, some issues around race in this book which may need a discussion)
The Hobbit
The Animals of Farthing Wood

As another option, DD also enjoyed getting a subscription to The Phoenix comic and currently gets The Week Junior, which is often read within hours of finding it on the door mat.

Eva Ibbotson! The Abominable is great, and Journey to The River Sea, and The Star of Kazam.

Yes to Louis Sachar! There's a boy in the girl's bathroom is my favourite book ever!

Joey Pigza Swallowed the Key

Hetty Feather, The Illustrated Mum, Queenie, Lily Alone and The Lottie Project are safe Jaqueline Wilsons for that age

Michael Morpurgos can be pretty harrowing - how tough is she? Maybe better for audiobooks you can listen to together so you can discuss afterwards.

My daughter loved The Boy at the Back of the Class and has just started Vi Spy, which she is also loving. She's started making her way through Narnia too.

Tamara Pierce is fabulous, but not "real life" (fantasy)
I know she's not popular these days, but has she tried Enid Blytons Adventure series? I loved Island of Adventure and similar stories at that age. You can explain that theyre of a time and some of the language isn't appropriate. My parents did the same and I found it easy enough to understand that. I also read a lot of pony books.
Alternatively how about the Anthony Horowitz Alex Rider stories? They're like a teenage bond...

Some really good stuff has been mentioned already. For recent real life books, I’d also suggest Katya Balen, Eve Ainsworth, Elle McNicoll, Libby Scott and Kelly Yang.

The London Eye Mystery- Siobhan Dowd,
Murder most Unladylike-Robyn Stevens,
The Girl who wasn't there-Karen McCrombie, The Northern Lights-Pbilip Pullman,
Wonder and Aiggie and Me- RJ Palicio

Also, if your daughter likes Adventure Stories, the Alex Bell has a series of books, the first being The polar Bears Explorers Club, fabulous!

My 10 yo loves Jacquline Wilson books, she started reading them around 8 or 9, they've definitely got grown up vibes!

Should say she progressed quickly to young adult books but that was cos 2 x DS had lots on offer.
Narnia, Phillip.pulman & Harry potter were good as well

Echoing other posters - Jacquline Wilson and Artemis fowl / northern lights trilogy. Narnia?

Other books I loved around that age:
Goodnight mister Tom
Carries War
A little princess
little women
secret garden
goosebumps
some of the older Michael Morpugo books?

At that age my DD moved onto Dork diaries & Percy Jackson for series. Local library & also Waterst9ones staff were great on giving suggestions for her to try out other types

Try:
Noel Steatfeild- Ballet Shoes, The Bell Family and many others
Hilary McKay- The Skylarks War, Binny books etc
Laura Ingalls Wilder- Little House on the Prairie series
Arthur Ransome- Swallows and Amazons and 11 other books in same series
The Railway Children
The Secret Garden

I love those my story ones and I’m 56.

Not really 'real life', but:

Narnia

Blyton's 'Adventure' series

Arthur Ransome

E. Nesbit

Noel Streatfeild

Frances Hodgson Burnett - Secret Garden and A Little Princess

Monica Edwards Romney Marsh series - don't know how available they are. The characters age through the series, but she's the right age for the first ones, when Tamzin the heroine is ten.

Antonia Forest - but I think she might be a bit young for them yet.

Otherwise, if she's into school stories, the Chalet School. Yes, adult Joey is insufferable, but the Austrian and wartime ones are well worth reading, I think.

Eva Ibbotson wrote books aimed at young children, at 11-12 yos, and adult romances. DD might like the 11-12 yo ones.

Karen McKombie’s Ally’s world series. I loved these.

Time travelling With a hamster by Ross welford was fab.
Polly Ho Yen is fab - Boy in the Tower was great albeit a bit sad. I did read this to a y5 class.
A Place called Perfect was another brilliant read!
oh. And The Nowhere Emporium. Amazing! But definitely quite fantastical.

I totally loved Nancy Drew at that age - is that something that might appeal to her?

It’s not exactly real-life (anyone knocked unconscious as frequently as Nancy is would have a fairly serious traumatic brain injury by now, and the amount of crime in River Heights strains credibility). But it isn’t witches and wizards, or dinosaurs coming for tea.

I have memories of the breathless descriptions of Nancy’s amazing hair getting a bit tedious, but I tended to skim over those parts and focus on the crime-solving.

The adventure island series by Helen moss 10 books in the series. My DD + DS love these

My daughter has just read the last bear and loved it. She also liked the boy at the back of the class, the night diary and when life gives you mangoes. I have also bought her the Judy blume fudge books but she has not started those yet.

I loved the Ramona Quimby books at that age. Still read them now!

The Lockwood & Co series by Jonathan Stroud. About a group of child ghost hunters. The books are no scarier than Harry Potter (I’ve been told the tv series is aimed at a slightly older age group though).

Oh and absolutely, 100% Jacqueline Wilson

The Lottie Brooks books and Pamela Burcharts series are popular with the year 5/6s at our school (PTA librarian). Skulduggery Pleasant if she's OK with peril (nonworse than some of the stuff in HP imo)