The win Sunday moved him past both Pete Sampras and William Renshaw, who each won seven Wimbledon titles.
'It's disbelief I can achieve such heights. I wasn't sure I would ever be here in another final after last year,' said Federer, who lost in the semifinals last year and took the rest of the season off to rest a knee injury.
'Here am I today with the eighth,' Federer added. 'It's fantastic, if you keep believing you can go far in your life.'
Federer, 35, was dominant against Cilic and throughout the tournament, not dropping a single set. It is the first time anyone has achieved that feat since Bjorn Borg in 1976.
This is Federer's first title at the All England Club since 2012. He now has 19 Grand Slam titles, having won both Wimbledon and the Australian Open this year.
In the women's draw on Saturday, Spain's Garbine Muguruza won her first Wimbledon title, defeating American Venus Williams in straight sets , 7-5, 6-0.
Spain';s Garbine Muguruza greets Venus Williams of the United States at the net after winning the Women';s Singles final match on day twelve at the Wimbledon Tennis Championships in London, July 15, 2017.
The 10th seeded Williams, 37, had been seeking to become the oldest women's Grand Slam champion but couldn't overcome the 14th seeded Muguruza.