Karaikkudi Junction (station code: KKDI) is an NSG–4 category Indian railway station in Madurai railway division of Southern Railway zone. It serves Karaikudi Municipal Corporation and its Karaikudi Urban Agglomoration areas, located in Sivaganga district of the Indian state of Tamil Nadu.

Karaikudi station was constructed as a part of Pudukkottai–Sivaganga railway line during the 1930s. Initially during its older days this station acted as an ordinary railway station when the Tiruturaipundi Aranthangi line was extended to Karaikudi, it became a junction railway station. It became as a junction by connecting all the three terminal lines they are Manamadurai Sivagangai Railway line, Trichinopoly Pudukkottai Railway line and Tiruturaipundi Aranthangi Railway line. Being a junction station, three rail lines emerge from the station, one towards Tiruchirappalli Junction, another to Thiruthuraipoondi junction and the third and final one Manamadurai Junction.

Being a Junction station, three rail lines emerge from the station, one towards Tiruchirappalli Junction, another to Manamadurai Junction and the third and final one towards Thiruthuraipoondi Junction.

It is a major as well as an important passing station present on the Tiruchirappalli–Manamadurai railway line. It also operates an inland container depot (railway goods shed) at Chettinad railway station.

For the FY 2022–23, the annual earnings of the station was ₹98,579,082 (US$1.2 million) and daily earnings was ₹270,080 (US$3,200). For the same financial year, the annual passenger count was 711,396 and daily count was 1,949. While, the footfall per day was recorded as 3,975.

Karaikudi is well connected with the capital city Chennai. Most of the trains bound to Chennai, Manamadurai, Rameswaram and Kanyakumari from Tiruchirappalli pass through this station, with every train having a stoppage here for a minimum of 5–10 minutes.

• BG single line towards Thiruvarur Junction – main line via Aranthangi, Pattukkottai, Thiruthuraipoondi Junction
• BG Electrified single line towards Tiruchirappalli Junction via Pudukkottai
• BG Electrified single line towards Manamadurai Junction via Sivaganga

Below projects are surveyed and waiting for funds since long time.

1. Madurai–Melur–Tirupattur–Karaikudi new BG line: Reconnaissance Engineering cum Traffic Survey for a new BG line between Karaikkudi and Madurai via Melur and Thirupattur (85.70 km) was conducted and Survey Report was sent to Railway Board on 27.11.2014. This project was shelved by Railway Board.

2. Karaikudi-Natham-Dindigul new BG line: Reconnaissance Engineering cum Traffic Survey for a new BG line between Karaikkudi and Dindigul via Thirupattur and Natham (105.60 km) was conducted and Survey Report was sent to Railway Board on 06.07.2015. This project was shelved by Railway Board.

3. Karaikudi-Devakottai-Ramanathapuram-Tuticorin new BG line: Reconnaissance Engineering cum Traffic Survey for a new BG line between Karaikkudi and Tuticorin via Devakkottai and Ramanathapuram (214.81 km) was conducted and Survey Report was sent to Railway Board on 30.08.2011. This project was shelved by Railway Board.