The 73-year-old actor, who is terminally ill with prostate cancer, managed to raise a smile as he thanked Hollywood for being "my home and my schooling".
"Everything I learned in life I learned from you. This means so much to me. Thank you very much everyone," continued the star, who told how he arrived in LA from Kansas aged 18.
Dennis was helped to the stage by a friend. He explained that the bandages on his arm and head were the result of a fall outside his home.
Famous faces among the hundreds-strong crowd at the ceremony included director David Lynch and Jack Nicholson, who wore a shirt emblazoned with images from Dennis' iconic film Easy Rider.
Adressing spectators was Viggo Mortensen, who kissed his friend of 20 years on the cheek before approaching the microphone. He called Dennis "a complete and fertile artist" who has been "a constant source of ideas, inspiration and humour for his friends and colleagues."
Dennis, who was given the go-ahead to attend the ceremony by his doctor, also shared his joy with his seven-year-old daughter Galen and 19-year-old son Henry.