Tina Turner –- It's MY WEDDING ... I'll Wear a GREEN DRESS If I Want To

Tina Turner became Mrs. Erwin Bach during a massive wedding ceremony in Switzerland this weekend ... but the bride wasn't dressed in white, she was lean and mean in green.

The 73-year-old singer had been shacking up with her 57-year-old beau for the past 27 years -- but finally decided to make it legal when he proposed to her in April. FYI -- Bach is a German music executive.

According to reports, 120 people attended the lakeside ceremony near Turner's home in Zurich -- including Oprah, David Bowie and Bryan Adams. The ceremony is said to have been "Buddhist-inspired."

As for Tina's dress, the emerald gold stunner was reportedly custom-designed by Giorgio Armani.