It is not possible to determine with any accuracy from any reliable historical documents or other sources when and by whom the original idol of the temple of Sri Padmanabhaswamy was consecrated.
The temple has references in the Puranas and epics and the Srimad Bhagwat states that Balarama visited this temple, bathed in Padmatheertha, and made many offerings. Nammalvar, a 9th-century poet and one of the 12 Vaishnava saints of the Alvar tradition, composed 10 hymns in praise of Lord Padmanabha. Padmanabha, some eminent scholars, writers, and historians, such as the late Dr. L. A. Ravi Varma of Travancore, have expressed the view that this temple was established on the first day of Kaliyuga (that is, 5,000 years ago).

The legend of the temple is mentioned in old palm leaf inscriptions, as well as in the famous text 'Anantasayana Mahatmya', that it was consecrated by a Tulu Brahmin monk named Divakara Muni. Name Mam. The idol was re-established in the 950th year of Kali Yuga. In the 960th Kali year, King Marthanda Varma built the Abhisravana Mandapam.
  
The legend about Diwakar Muni, a great Vishnu devotee, is that he had visions of the child Krishna who always played around him. Once, the child's mischief distracted the sage and he scolded the child. At this, the child Krishna disappeared, and while leaving he asked the sage to find him at Ananta Kaadu. The rishis started searching for the child, finally, the muni found the child Krishna inside the Pe Iluppa tree, which fell down assuming the form of a reclining Vishnu about 18 meters tall.
  
The recumbent idol of Lord Padmanabha can be viewed through three doors—one for the face, one for the belly from which a lotus emerges, and one for the feet.
 

Service and Worship:
The temple remains open from 3.30 am to 7.30 pm; It remains closed between 12 noon to 5 pm. The best time to visit is between 6.30 pm to 7 pm, when the priests light lamps around the temple.

Celebration

• Vishu: The main event of the temple, the Malayalam New Year's Day, attracts many devotees here.
• Thiruvonam: This is one of the most prominent traditional celebrations of this temple as it is the birthday of Sri Padmanabhaswamy.
• Shri Krishna Janmashtami: The birthday of Shri Krishna Swamy in Rohini Nakshatra on Ashtami of Bhadrapada Krishna Paksha is specially celebrated in the month of August-September all over India. The temple opens early till 2 in the morning. Many images of Lord Krishna are kept inside the temple. It is believed that if a childless couple offers the puja, they will be blessed with a child.
• Navaratri Celebrations: The idol of Sri Saraswathi Devi is brought from Padmanabhapuram Palace in Kanyakumari district and traditionally worshiped at Valiya Kottaram Complex, Thiruvananthapuram.
• Sri Kumaraswamy from Kumarakovil and Sri Munnuttinanga from Suchindram also join them in a grand palanquin procession.
• Valiya Ganapathi Homam: This is performed two days before the start of Navaratri festival, for 12 days.
• Alpasi Ulsavam: Sree Padmanabhaswamy Temple celebrates bi-annual festivals in the months of Thulam and Meenam. A formal ceremony is held to sanction the festival, called anna. The ten-day festival begins with the hoisting of the flag on the gold pole of Sri Padmanabhaswamy and the silver flag pole of Sri Krishnaswamy.
• Swarga Vathil Ekadashi: Vaikuntha Ekadashi also known as Swarga Vathil Ekadashi is an auspicious day for devotees of Maha Vishnu. A crowd of people throngs the temple on this day. There is special worship, prasad and dinner. The temple remains open for longer hours.
• Maha Shivratri: This is a day that is celebrated all over India as significant for Lord Shiva. On this day special anointing is done to Shiva who resides in the sanctum sanctorum.
• Sri Ved Vyas Jayanti: Sri Ved Vyas Jayanti is celebrated on the full moon day of Kartik in honor of the great sage Vyasa.
• Lakshdeepam festival: On this day the whole temple is decorated with thousands of lamps. The first Lakshadeepam festival was organized by King Marthanda Varma in a grand manner with much fanfare.
   
  Best Time To Visit: Throughout the year.

Interesting fact

• King Marthanda Varma dedicated his kingdom to Lord Padmanabha and ruled the kingdom himself only as a representative.
• The unique feature of this temple is that Vishnu and Shiva are in the same place.
• Dress code for temple entry: Men in dhoti and angavastra (shirts are not allowed) and women should wear saree.
  
  Nearby places
• Neyyattinkara Temple: 20 km south of Thiruvananthapuram city in Kerala is Sri Krishna Swamy.
• Attukal Bhagavathy: There is an ancient temple of the goddess in the city of Thiruvananthapuram.
• Sri Janardhana Temple: The 13th-century Janardhana Swamy temple exists.
• Agastyakoodam: It is believed to be the abode of Trishi Agastya.