Its display business is estimated to have contributed 1 trillion won on strong demand for LCD panels in China.
Though LG did not elaborate on its forecasts, analysts say LG's mobile business likely turned an operating loss for the eighth-straight quarter.
Samsung, in a regulatory filing, said its January-March profit was likely 9.9 trillion won ($8.76 billion), compared with an average forecast of 9.4 trillion won from a Thomson Reuters survey of 18 analysts.
The third-generation leader of South Korea's top conglomerate was mostly silent at his first court appearance in what has been called the "trial of the century", as his lawyers labored to portray him as an innocent bystander in a graft scandal.
Prosecutors believe the 48-year-old billionaire and his aides used Samsung corporate funds to bribe former President Park Geun-hye and her close confidante in exchange for supporting a smooth leadership transition at Samsung.
For many months, Samsung (SSNLF) has been embroiled in a wave of bitter controversies ranging from corruption charges waged at senior management to the widespread Galaxy Note 7 recall.
S Korea test fires 800km-range missile
The North's latest missile launch also came during annual military drills between the United States and South Korea. Since taking office, Trump has left open the possibility of military action against North Korea.
Lee faces five charges that could entail at least five years in prison if he is found guilty.
Millions of South Koreans taking part in weekly street rallies demanding Park's removal have also called for the arrest of the tycoons involved in the scandal, including the leaders of Hyundai, SK and Lotte.
Growing demand for more firepower from devices such as smartphones and servers have also helped push up margins for Samsung and its rivals in recent quarters.
Samsung is reporting its best first quarter earnings since 2013, with the main source of revenue coming from memory chips and OLED display sales.
South Korea's LG Electronics Inc 066570.KS estimated on Friday its first-quarter operating profit rose 82 percent to its highest in almost eight years, handily beating market expectations on healthy sales of appliances and televisions. It is scheduled to give more details including quarterly net profit later in the month.
The performance of Samsung's Galaxy S8 premium smartphone, which goes on sale on April 21, will be the key variable for Samsung going forward. The S8 was its first major smartphone launch since the fire-prone Galaxy Note 7 fiasco.