proxy_address = "ip:port"
proxy_username = "kullanici adi"
proxy_password = "sifre"


proxy = Proxy()
proxy.proxy_type = ProxyType.MANUAL
proxy.http_proxy = proxy_address
proxy.ssl_proxy = proxy_address
proxy.socks_proxy = proxy_address

if proxy_username and proxy_password:
    proxy.ssl_proxy = f"{proxy_username}:{proxy_password}@{proxy_address}"


chrome_options = webdriver.ChromeOptions()
chrome_options.add_argument("--proxy-server={}".format(proxy.http_proxy))


driver = webdriver.Chrome(options=chrome_options)


driver.get("https://www.r10.net/python/3792956-python-selenium-proxy-baglantisi.html")


driver.quit()

from selenium import webdriver
PROXY = "11.456.448.110:8080"
chrome_options = WebDriver.ChromeOptions()
chrome_options.add_argument(f'--proxy-server={PROXY}')
chrome = webdriver.Chrome(chrome_options=chrome_options)
chrome.get("https://www.google.com")

Bu şekilde yapabilirsiniz. Bir siteden aldım kodu ama kendim de kullandım daha önce çalışıyor.