The 25-year-old won the world indoor pentathlon title and Commonwealth Games heptathlon crown this year, but is yet to conquer a world-class field.
World and Olympic champion Nafi Thiam stands in the way and it will be the first time Johnson-Thompson has faced the Belgian since coming fifth at last year's World Championships.
Anouk Vetter and Caroline Schafer - who complete the top three in the world - will also compete in Berlin on Thursday and Friday, a huge leap in quality from the fields in Birmingham and Australia.
And, after disappointments at the 2015 and 2017 World Championships and 2016 Olympics, Johnson-Thompson knows it is now time to shine.
She told Press Association Sport: "It's why I'm so focused. It would be very easy to say I've had a good season and just glide along into the Euros.
"I really want to do well and push myself for more, not just including Berlin but next year and Tokyo (at the Olympics in 2020).
"Everyone in heptathlon hasn't got a perfect seven events. Nothing is certain and you have to concentrate on your own events.
"Mine and Thiam's strengths and weaknesses are kind of the same. We both have a strong high jump, she has a strong javelin and her long jump is getting better.
"I have a better 200m and 800m. We have different strengths and weaknesses, but it's who gets the best on the day and she's been able to recreate that time after time.
"That's something I've not yet done and what I'm trying to do."
The Liverpudlian has been training and living in Montpellier for almost two years and believes it is paying off.
She said: "It's definitely taken me time to settle in, but now I can see the vision, the different techniques I need to do, my body is used to the training and I'm mentally happier living in France. It's definitely all coming together."
She set herself a target of two golds and one other medal from her three main championships this year.
With two victories in the bag she is closing in on her goal, with the Europeans this week, but remains cautious over what would be a success.
"I want to win medals and I've always done special one-off things in certain events but missed out on the medals," said Johnson-Thompson.
"This year was about winning medals and that is what I want to do in Berlin.
"It depends how the medals come about, you don't know what points score they'll be. I don't know what I'd be happy with but I want a medal."
Katarina Johnson-Thompson is an ambassador for QIPCO British Champions Series. For more information visit britishchampionsseries.co
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