The world number one defeated her Spanish opponent to win her 6th title at SW19 and 21st Grand Slam title.
Williams is on course for a calender Grand Slam after wining the Australian and French Open title.
“It Feels So Good”
Williams withstood a late fightback from 20th seed Muguruza, to come through in one hour and 23 minutes.
After receiving the trophy she said: “It feels so good holding the trophy. I have to give thanks to Jehovah God for the day. I just really relied on His strength.
“Garbine! She played so well I didn’t even know it was over because she was fighting so hard in the end…
“Congratulations! Don’t be sad. You will be holding this trophy very, very soon believe me. You are a great champ.
“I am just happy it was such a great match”.
She will head to the US Open next month, aiming to complete the first calendar year Grand Slam of her career.
Williams thrashed Maria Sharapova to reach the final, extending her winning run against Sharapova to 17 matches over 11 years with a 6-2, 6-4 victory.
Muguruza, who is 21-years-old, was playing in her first Grand Slam final and took a 4-2 lead, before giving the top seed a mighty scare by battling back from a set and 5-1 down with two breaks of serve.
She became the first Spanish woman to reach the Wimbledon final since 1996 when she beat Poland’s Agnieszka Radwanska 6-2, 3-6, 6-3.
In the men’s championship, Roger Federer defeated Andy Murray in the semi-final match on Friday to book a place in the final.