The fourth seed survived some heavy hitting from her opponent to beat the world No47 6-3 6-7 (3-7) 6-2 on Centre Court at the All England Club.
Sharapova, the 2004 champion at SW19, will face either Serena Williams or Victoria Azarenka for a place in the final.
“There really is [a special feeling],” said Sharapova. “I had a really tough match last year against [Angelique] Kerber. I really felt like, although I lost in the fourth round, everyone always looks at results, my game on grass had really improved in the years before. I really felt confident.
“It was tough because I felt a few points could have changed things around. From then on you really never know how things evolve, what chances you might have. That was a bit disappointing.
“But overall I’m really happy I was able to take that loss and move up a few steps further this year.”
Elsewhere, Spain’s Garbine Muguruza beat Timea Bacsinszky in straight sets to book her spot in the semi-finals.
The 21-year-old 20th seed won 7-5 6-3 to reach the last four of a Grand Slam for the first time.
“It is just amazing. I am so happy. It was a very tough match and I am just so excited. The last game was very intense,” said Muguruza.
“It is very hard to make the last four of Wimbledon, so to achieve this I am very proud.”
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