Last year, the city scored a 70 on the index, not receiving any of the 18 points awarded in the non-discrimination laws category. Earning all of those points along with points in other categories yielded a score of 100 this year.
Phoenix Mayor Greg Stanton said the score sends a message to all city residents.
"Every single person in our city is fully supported no matter what neighborhood you grew up in, no matter your socioeconomic class, no matter your ethnicity, no matter your sexual orientation," he said.
Kathy Young, political co-chair for the Human Rights Campaign Arizona, said Stanton and the City Council worked closely with her organization after last year's index.
"They worked hard to make sure that there were laws on the books and ordinances in place, and whatever they needed to do to close the gaps in equality," she said.
The categories covered by the index are: non-discrimination laws, relationship recognition, municipality as an employer, municipal services, law enforcement and relationship with the LGBT community.
Angela Hughey, co-founder and president of ONE Community, an organization advocating for the lesbian, gay, bisexual and transgender community, said that the anti-discrimination ordinance and the recognition from the Human Rights Campaign are a step in the right direction for Phoenix.
"Phoenix is the sixth-largest city in the nation, and it's imperative that we are inclusive of all of our diverse citizens and celebrate all of our diverse citizens," she said. "We're a travel destination and we're a business destination, and it's really important if we want to be a top-tier city that we are inclusive of everyone. So this is an incredibly important step and recognition for the city of Phoenix."
Hughey said that Phoenix can help other Valley communities that received lower scores.
"Phoenix, being the largest city in Arizona, can really reach out to municipalities and towns that are nearby and kind of lend knowledge on how these cities and towns can also move toward being fully inclusive," she said.
Stanton said that he wants all cities in the region to do as well as Phoenix has in terms of equality.
"If other mayors or other leaders of other cities would like to look at what Phoenix is doing, we will always been open and appreciative of other cities that want to learn best practice from us, just as we should learn best practices from other cities," he said.
Phoenix was the only Arizona city to receive a perfect score, though Tucson wasn't far behind with a 90.
Tempe received a 72, while the other Arizona cities ranked, Mesa, Gilbert, Scottsdale, Chandler and Glendale, received scores of less than 50.
Leah Powell, community resources and diversity manager for Chandler, which received a 22, said city officials were disappointed with the score and that the Human Rights Campaign didn't look at all the materials that Chandler submitted.
Julie Frisoni, executive communication director for Glendale, which received a 13, said she hadn't heard that the index was being compiled. Upon looking at the scorecard, Frisoni said that the information wasn't accurate and that she didn't believe it to be a fair representation of the city.