The 26-year-old joined Rangers midway through last season, and said she was delighted to be offered the new deal to stay at the club until summer 2021.
Speaking to RangersTV, she said: “I am delighted to get it over the line, I’ve really enjoyed my six months here so far and when Greg and Amy offered me the new contract I was delighted to sign.
“I think it is exciting, I love the ambition of the club, it is an exciting time to be involved with Rangers. I know there is going to be a lot of changes come January but it is exciting moving forward and looking to hopefully challenge next season.
With the new additions to the squad, and many with experience of winning silverware in Scotland, Brownlie is hoping it can help push Rangers to success.
She added: “I think that is important, I think when you have that sort of experience especially winning silverware in this country it makes it a lot better for players moving forward. It also helps the ones who maybe haven’t potentially won any silverware.
“Rangers are a huge club in Scotland which everyone knows, so I think it is very exciting times and obviously the changes that are happening right now are very exciting for women’s football.
“Every competition you go into you want to win and I think with Greg and Amy they are building a strong squad going into next season.
“I think for Rangers we want to go forward and get into the Champions League and take it to the highest level that we possibly can.”