The Big Little Lies actress attending a showing alongside friends and raved about the experience on Twitter.
Dear Haven Hansen songwriter Benj Pasek took this photo of Bey and Platt, which Platt went on to share on Instagram.
Jesse Tyler Ferguson went to see the show back in June.
On the same night as Jesse Tyler Ferguson, Chloë Grace Moretz was also at the show. Platt posted photos with both celebs with the caption, "These beautiful peeps came to share @dearevanhansen with us tonight."
"Thanks for joining us tonight at @DearEvanHansen, @jessicachastain! Your class/kindness/elegance called for black and white," Platt wrote when Jessica Chastain stopped by to see the show.
"This man graced us with his presence for a second time tonight, and if you think I formed good/coherent/meaningful sentences when he was kind enough to come say hello afterward, you'd be very wrong. I got it together enough to smile. Staggered by this legend and his goodness," Platt wrote alongside a pic with Morgan Freeman.
After Platt wont the Tony Award for his work in the show, Blake posted a photo with Platt. "Congratulations @bensplatt & @dearevanhansen Thank you, Ben for showing -each night- how extraordinary it is when someone is unapologetically unique. To all the "strange" ones out there --- You are not alone. #YouWillBeFound."
When Jimmy Fallon saw the show on Valentine's Day, Platt posted this pic thanking him. "Thanks for spending your Valentine's Day @DearEvanHansen, sir @jimmyfallon," Platt wrote.
Platt was left speechless when Julianne Moore attended the show. "I mean why caption cause there are no words," he wrote alongside a photo with Moore.
"It simply doesn't get better than @whoopigoldberg," Platt wrote when Whoopi Goldberg stopped by the show. "As remarkably kind and wise as she is legendary. An honor to have you in the house tonight."
RuPaul stopped by to see the show and Platt shared this pic of the two together backstage. "All hail the queen," Platt wrote on Instagram.
"Thank you @melissamccarthy for taking the time to see @DearEvanHansen the day after making comedy history. Your kindness and talent are overwhelming and our cast has never been more excited and joyful," Platt wrote alongside a pic with Melissa McCarthy.
When Zac Efron stopped by to see the show, Platt posted this picture on Instagram. "Troy Bolton came to see @DearEvanHansen and middle school Ben had a freak out (so did 23 year old Ben). And did he wear a @DearEvanHansen scarf? Bet on it. Bet on it," he captioned the pic.
"How To Lose Your Cool in 10 Seconds," Platt captioned this picture with Kate Hudson.
"Mostly this was important because I finally got to gush about this woman's brilliance in La La Land," Platt wrote on Instagram. "Thank you for coming to the show and for your kindness and talent, both of which are incredibly inspiring. #DearEvanHansen."
When Mindy Kaling called the show the "best thing" she's ever seen, Platt replied with a sweet message on Instagram. He wrote, "Thank you @mindykaling for your unbelievable kindness and also I watched Mindy Project between shows so thank you for that too!!!!"